RuntimeCustomAttributeData doesn't distinguish field/property metadata

https://github.com/dotnet/runtime/blob/3898c7135c4dc861e00f49285d0c275f69e2e6c5/src/coreclr/System.Private.CoreLib/src/System/Reflection/RuntimeCustomAttributeData.cs#L730-L736

This is validated, but not actually used. Property aliasing a field could materialize wrong Property/Field Info.

This is trivial to fix but this code is in the process of getting unified with native AOT so do not assign to copilot this year (pull requests are in flight right now and there might be more and this will be a very unnecessary merge conflict).

Start in src/coreclr/System.Private.CoreLib/src/System/Reflection/RuntimeCustomAttributeData.cs at lines 730-736, then read the surrounding metadata handling. Check where the validated field/property distinction is used and verify that aliased fields do not materialize the wrong PropertyInfo or FieldInfo. Coordinate with the in-flight native AOT unification work before changing this area.

Written by the indexing model from the issue text.