Permission validation errors are opaque

[slifty]

@bickelj pointed this out in an earlier review but I didn't properly make an issue.

Right now because of how our schema validation works our permission grant API responds with very confusing messages about what is wrong (basically it is returning all possible validation errors for all possible types of permission grant, which is profoundly unhelpful).

This needs to be resolved; it may be that the core problem is that shema shape is not the right place to encode value validation (e.g. the schema doesn't need to define what combinations of values / attributes are expected). That said, there may be other solutions too.

Here's an example of what I mean by opaque:

{
  "name": "InputValidationError",
  "message": "Invalid request body.",
  "details": [
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/0/required",
      "keyword": "required",
      "params": {
        "missingProperty": "funderShortCode"
      },
      "message": "must have required property 'funderShortCode'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/1/required",
      "keyword": "required",
      "params": {
        "missingProperty": "granteeKeycloakOrganizationId"
      },
      "message": "must have required property 'granteeKeycloakOrganizationId'"
    },
    {
      "instancePath": "/granteeUserKeycloakUserId",
      "schemaPath": "#/oneOf/2/properties/granteeUserKeycloakUserId/format",
      "keyword": "format",
      "params": {
        "format": "uuid"
      },
      "message": "must match format \"uuid\""
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/3/required",
      "keyword": "required",
      "params": {
        "missingProperty": "granteeKeycloakOrganizationId"
      },
      "message": "must have required property 'granteeKeycloakOrganizationId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/4/required",
      "keyword": "required",
      "params": {
        "missingProperty": "dataProviderShortCode"
      },
      "message": "must have required property 'dataProviderShortCode'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/5/required",
      "keyword": "required",
      "params": {
        "missingProperty": "granteeKeycloakOrganizationId"
      },
      "message": "must have required property 'granteeKeycloakOrganizationId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/6/required",
      "keyword": "required",
      "params": {
        "missingProperty": "opportunityId"
      },
      "message": "must have required property 'opportunityId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/7/required",
      "keyword": "required",
      "params": {
        "missingProperty": "granteeKeycloakOrganizationId"
      },
      "message": "must have required property 'granteeKeycloakOrganizationId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/8/required",
      "keyword": "required",
      "params": {
        "missingProperty": "proposalId"
      },
      "message": "must have required property 'proposalId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/9/required",
      "keyword": "required",
      "params": {
        "missingProperty": "granteeKeycloakOrganizationId"
      },
      "message": "must have required property 'granteeKeycloakOrganizationId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/10/required",
      "keyword": "required",
      "params": {
        "missingProperty": "proposalVersionId"
      },
      "message": "must have required property 'proposalVersionId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/11/required",
      "keyword": "required",
      "params": {
        "missingProperty": "granteeKeycloakOrganizationId"
      },
      "message": "must have required property 'granteeKeycloakOrganizationId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/12/required",
      "keyword": "required",
      "params": {
        "missingProperty": "applicationFormId"
      },
      "message": "must have required property 'applicationFormId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/13/required",
      "keyword": "required",
      "params": {
        "missingProperty": "granteeKeycloakOrganizationId"
      },
      "message": "must have required property 'granteeKeycloakOrganizationId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/14/required",
      "keyword": "required",
      "params": {
        "missingProperty": "applicationFormFieldId"
      },
      "message": "must have required property 'applicationFormFieldId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/15/required",
      "keyword": "required",
      "params": {
        "missingProperty": "granteeKeycloakOrganizationId"
      },
      "message": "must have required property 'granteeKeycloakOrganizationId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/16/required",
      "keyword": "required",
      "params": {
        "missingProperty": "proposalFieldValueId"
      },
      "message": "must have required property 'proposalFieldValueId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/17/required",
      "keyword": "required",
      "params": {
        "missingProperty": "granteeKeycloakOrganizationId"
      },
      "message": "must have required property 'granteeKeycloakOrganizationId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/18/required",
      "keyword": "required",
      "params": {
        "missingProperty": "sourceId"
      },
      "message": "must have required property 'sourceId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/19/required",
      "keyword": "required",
      "params": {
        "missingProperty": "granteeKeycloakOrganizationId"
      },
      "message": "must have required property 'granteeKeycloakOrganizationId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/20/required",
      "keyword": "required",
      "params": {
        "missingProperty": "bulkUploadTaskId"
      },
      "message": "must have required property 'bulkUploadTaskId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/21/required",
      "keyword": "required",
      "params": {
        "missingProperty": "granteeKeycloakOrganizationId"
      },
      "message": "must have required property 'granteeKeycloakOrganizationId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/22/required",
      "keyword": "required",
      "params": {
        "missingProperty": "changemakerFieldValueId"
      },
      "message": "must have required property 'changemakerFieldValueId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf/23/required",
      "keyword": "required",
      "params": {
        "missingProperty": "granteeKeycloakOrganizationId"
      },
      "message": "must have required property 'granteeKeycloakOrganizationId'"
    },
    {
      "instancePath": "",
      "schemaPath": "#/oneOf",
      "keyword": "oneOf",
      "params": {
        "passingSchemas": null
      },
      "message": "must match exactly one schema in oneOf"
    }
  ]
}