Several improvements for read search

[orgads]

This PR includes 3 features in read_search, and 2 other changes, which are required for supporting voxbone api.

read_search features:

• Support id_attribute
• Support {id} substitution also for search_value in read_search
• Support object_wrap

Other changes:

• Support slash separator for ignore_changes_to
• Strip null values when comparing read output if they're not set in the input.

Some providers use a different notation for the object on create/update and on read.

Full example for Voxbone voiceuri api follows.

Sample PUT request:

PUT /configuration/voiceuri

Data:

{
  "voiceUri": {
    "voiceUriProtocol": "SIP",
    "uri": "[email protected]",
    "description": "desc"
  }
}

Response is the same, but with voiceUriId in voiceUri.

GET sample:

GET /configuration/voiceuri/1234

{
  "voiceUris": [
    {
      "voiceUriId": 1234,
      "backupUriId": null,
      "backupUri": null,
      "voiceUriProtocol": "SIP",
      "uri": "[email protected]",
      "description": "desc"
    }
  ],
  "resultCount": 1
}

Notice that read doesn't have an internal voiceUri in voiceUris array.

Sample provider configuration:

provider "restapi" {
  uri                   = "https://api.voxbone.com/v1"
  create_method         = "PUT"
  update_method         = "PUT"
  create_returns_object = true
  write_returns_object  = true
}

resource "restapi_object" "voxbone_voice_uri" {
  path         = "/configuration/voiceuri"
  id_attribute = "voiceUri/voiceUriId"
  ignore_changes_to = ["voiceUri/voiceUriId"]

  read_search = {
    results_key = "voiceUris"
    search_key  = "voiceUriId"
    search_value = "{id}" # Support for this substitution is new
    id_attribute = "voiceUriId" # New
    object_wrap = "voiceUri" # New
  }

  data = jsonencode({
    voiceUri = {
      uri              = "[email protected]"
      voiceUriProtocol = "SIP"
      description      = "desc"
    }
  })
}

[orgads]

I tried to write acceptance tests, but couldn't get it to work. Some guidance can be useful :)

I can split the separator commit to a separate PR if you prefer that. It's unrelated to the rest, just did it for consistency.

The id substitution can also be separated if you wish.

[orgads]

ping?