Data schema/fix custom type array bug

[TimRoadley]

Problem

This PR fixes issue 3330, where generated GraphQL output is wrong for mutation with array of customType.

Before the fix, resource.ts causes TodoUpsertInput to be generated incorrectly without an array type.

export type TodoUpsertInput = {
  content?: string | null,
  tags?: TodoTagTypeInput | null,
  updatedTs?: number | null,
};

After the fix, TodoUpsertInput is generated properly with the Array type:

export type TodoUpsertInput = {
  content?: string | null,
  tags?: Array< TodoTagTypeInput | null > | null,
  updatedTs?: number | null,
};

Note that this fix was required to generate the schema properly in the first place. Without this fix, the AppSync schema is generated incorrectly to begin with, setting up codegen for failure when it generates the client side code.

Changes

The only fixes required are in packages/data-schema/src/SchemaProcessor.ts, the other changes in this PR were required for the push to work and can otherwise ideally be ignored / omitted.

Validation

Unit tests have been added for this new functionality.

Checklist

• [x ] If this PR includes a functional change to the runtime or type-level behavior of the code, I have added or updated automated test coverage for this change. (see Testing Strategy README)
• [ x] If this PR requires a docs update, I have linked to that docs PR above. (not required)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[ahmedhamouda78]

I am guessing this comment was generated by an LLM. Can you please review/remove all such comments?

[ahmedhamouda78]

Can you also please add the missing props to the "Enum" type on line 1422?

[ahmedhamouda78]

Can you please remove any unnecessary white space changes irrelevant to the fix itself from the PR?

[ahmedhamouda78]

Thank you for adding tests! Can you also add test coverage to the ModelSchema.test.ts file as it is more focused on testing custom operations argument inputs? You can refer to PR #617 for these tests