Move schema store into service and add schema keys

[captainsafia]

This pull request renames the OpenApiComponentService to OpenApiSchemaService and introduces OpenApiSchemaStore service to support managing the storage/retrieval of schemas in the cache. It also introduces an OpenApiSchemaKey type to support referencing keys in the schema.

Key Changes:

• Refactoring of Services:
  • src/OpenApi/src/Extensions/OpenApiServiceCollectionExtensions.cs: Replaced OpenApiComponentService with OpenApiSchemaService and added OpenApiSchemaStore in the AddOpenApiCore method.
  • src/OpenApi/src/Services/OpenApiDocumentService.cs: Replaced OpenApiComponentService with OpenApiSchemaService.
  • src/OpenApi/src/Services/Schemas/OpenApiSchemaService.cs: Renamed from OpenApiComponentService.cs, refactored to use OpenApiSchemaStore and OpenApiSchemaKey. [1] [2] [3] [4]
  • src/OpenApi/src/Services/Schemas/OpenApiSchemaStore.cs: New class to store schemas generated by the JsonSchemaMapper for a given OpenAPI document for later resolution.
• Introduction of new Types:
  • src/OpenApi/src/Services/Schemas/OpenApiSchemaKey.cs: New record struct introduced to represent a unique identifier for storing and retrieving JSON schemas.
• Changes in Tests:
  • src/OpenApi/test/Extensions/OpenApiServiceCollectionExtensionsTests.cs: Updated the assertions to check for OpenApiSchemaService instead of OpenApiComponentService. [1] [2] [3] [4] [5] [6]
  • src/OpenApi/test/Services/OpenApiDocumentServiceTestsBase.cs: Updated the TestServiceProvider class to use OpenApiSchemaService and OpenApiSchemaStore, and updated the GetKeyedService and GetRequiredKeyedService methods accordingly. [1] [2]