OpenAPI/ApiExplorer: Fix paths without binding in Minimal Api's not discovered

[desjoerd]

Paths without a binding would be omitted by the EndpointMetadataApiDescriptionProvider. Some tests around OpenApi required fixing as arrays are not supported in paths.

Fixes #63883

[Copilot]

Pull Request Overview

This PR addresses an issue where paths without binding in Minimal APIs were not being discovered in the API explorer. The fix ensures route parameters are properly tracked and adds missing ones to the API description when they aren't associated with delegate parameters.

Key changes:

• Modified EndpointMetadataApiDescriptionProvider to track and add unbound route parameters
• Removed array parameter test cases from path parameter tests since arrays aren't supported in path parameters
• Added comprehensive test coverage for query parameters and validation attributes
• Enhanced test assertions to verify parameter location (Path vs Query)

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/Mvc/Mvc.ApiExplorer/src/EndpointMetadataApiDescriptionProvider.cs	Core fix to track remaining route parameters and add them to API description
src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Services/OpenApiSchemaService/OpenApiSchemaService.ParameterSchemas.cs	Updated tests to remove invalid array path parameters, added query parameter tests, and enhanced assertions
src/OpenApi/test/Microsoft.AspNetCore.OpenApi.SourceGenerators.Tests/OperationTests.MinimalApis.cs	Added test case for route parameters from Minimal APIs
src/OpenApi/test/Microsoft.AspNetCore.OpenApi.SourceGenerators.Tests/snapshots/OperationTests.SupportsRouteParametersFromMinimalApis#OpenApiXmlCommentSupport.generated.verified.cs	Generated snapshot file for XML comment support

[dotnet-policy-service]

Thanks for your PR, @@desjoerd. Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[desjoerd]

Tests will fail till #63872 is merged, as that adds the correct condition for path parameters without model metadata.

I am adding unit tests for the ApiExplorer, just looking at how does fit together :)

[desjoerd]

Unit tests added. Let me know what to change or whether this change is desired 👍.

Note for the reviewers:
I moved/changed some test cases which used arrays in the path, that is not supported in the routing so I moved those cases in a new test for query parameters.