Add special handling for array types in OpenAPI schema references.

[marcominerva]

This pull request enhances the handling of array types in OpenAPI schema reference IDs and updates the corresponding unit tests to cover these scenarios. The most important changes are grouped below:

Schema Reference ID Generation:

• Added special handling in JsonTypeInfoExtensions.cs so that array types (e.g., string[]) now generate schema reference IDs ending with Array instead of using invalid characters for OpenAPI schema keys. For example, string[] becomes stringArray, and string[][] becomes stringArrayArray.

Unit Test Coverage:

• Updated JsonTypeInfoExtensionsTests.cs to add test cases for types like Ok<string[]>, Ok<int[]>, Ok<Todo[]>, and Ok<string[][]>, ensuring the new schema reference ID logic for arrays is properly tested.

Fixes #66299

[Copilot]

Pull request overview

This PR fixes OpenAPI schema reference ID generation for array types so the resulting component schema keys avoid invalid characters like [], aligning with OpenAPI’s component key constraints and addressing #66299.

Changes:

• Updated GetSchemaReferenceId(Type, ...) to special-case arrays by appending Array to the element type’s schema ID (including jagged arrays).
• Added unit test coverage for array generic arguments such as Ok<string[]>, Ok<int[]>, Ok<Todo[]>, and Ok<string[][]>.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/OpenApi/src/Extensions/JsonTypeInfoExtensions.cs	Adds array-specific schema reference ID formatting to avoid invalid OpenAPI component schema key characters.
src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Extensions/JsonTypeInfoExtensionsTests.cs	Extends test data to validate schema reference IDs produced for array-based generic result types.

[mikekistler]

Looks good! 👍

Thanks for this fix!