Unify enum and union member comparison types (#55377)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/55377

Simplifies the member comparison logic by consolidating enum and union member types into a single discriminated union. This reduces code duplication and makes the comparison result handling more uniform across the codebase, as both member types now follow the same pattern with a `memberKind` discriminator.

When D86501597 was added, we couldn't come up with an easy way to converge these, so it was easier to just duplicate the code path for enum for unions. It always felt like a smell to me though, because they are so similar. AI was able to find a good way to converge them.

Changelog: [Internal]

Reviewed By: makovkastar

Differential Revision: D91296850

fbshipit-source-id: 5a1baf1c8149f0c6c9c72c0dce9ea093f71e39cd