Handle more Attribute Types when Filtering Assemblies

[dellis1972]

Fixes #9369

When System.Reflection.Metadata comes across an Attribute which has a generic, it does NOT return a TypeReferenceHandle. It returns a TypeSpecificationHandle.

Tying to cast the type results in the following error

System.InvalidCastException: Die angegebene Umwandlung ist ungültig.
error XAFLT7007:    bei System.Reflection.Throw.InvalidCast()
error XAFLT7007:    bei System.Reflection.Metadata.TypeReferenceHandle.op_Explicit(EntityHandle handle)
error XAFLT7007:    bei Xamarin.Android.Tasks.MetadataExtensions.GetCustomAttributeFullName(MetadataReader reader, CustomAttribute attribute)
error XAFLT7007:    bei Xamarin.Android.Tasks.FilterAssemblies.IsAndroidAssembly(AssemblyDefinition assembly, MetadataReader reader)
error XAFLT7007:    bei Xamarin.Android.Tasks.FilterAssemblies.ProcessAssembly(ITaskItem assemblyItem, List`1 output)
error XAFLT7007:    bei Xamarin.Android.Tasks.FilterAssemblies.RunTask()
error XAFLT7007:    bei Microsoft.Android.Build.Tasks.AndroidTask.Execute()

So we need to handle this case, and put in place a backup to handle an InvalidCastException so that we never hit this issue again.

[jonpryor]

Draft commit message:

[Xamarin.Android.Build.Tasks] Support HandleKind.TypeSpecification (#9373)

Fixes: https://github.com/dotnet/android/issues/9369

[C# 11 added support for generic custom attributes][0]:

	[AttributeUsage(AttributeTargets.Assembly, AllowMultiple = true, Inherited = false)]
	public class GenericTestAttribute<T> : Attribute {
	}

which means generic types can now be used as assembly-level attributes:

	[assembly: GenericTestAttribute<string>]

Unfortunately, attempting to do this would result in an
`InvalidCastException` from the `<FilterAssemblies/>` task:

	System.InvalidCastException: Die angegebene Umwandlung ist ungültig.
	error XAFLT7007:    bei System.Reflection.Throw.InvalidCast()
	error XAFLT7007:    bei System.Reflection.Metadata.TypeReferenceHandle.op_Explicit(EntityHandle handle)
	error XAFLT7007:    bei Xamarin.Android.Tasks.MetadataExtensions.GetCustomAttributeFullName(MetadataReader reader, CustomAttribute attribute)
	error XAFLT7007:    bei Xamarin.Android.Tasks.FilterAssemblies.IsAndroidAssembly(AssemblyDefinition assembly, MetadataReader reader)
	error XAFLT7007:    bei Xamarin.Android.Tasks.FilterAssemblies.ProcessAssembly(ITaskItem assemblyItem, List`1 output)
	error XAFLT7007:    bei Xamarin.Android.Tasks.FilterAssemblies.RunTask()
	error XAFLT7007:    bei Microsoft.Android.Build.Tasks.AndroidTask.Execute()

This happens because when System.Reflection.Metadata comes across an
Attribute which has a generic type parameter, it does *not* return a
[`TypeReferenceHandle`][1], but instead a
[`TypeSpecificationHandle`][2].

Update `MetadataExtensions.GetCustomAttributeFullName()` to support
[`HandleKind.TypeSpecification`][3]

[0]: https://learn.microsoft.com/dotnet/csharp/whats-new/csharp-11#generic-attributes
[1]: https://learn.microsoft.com/dotnet/api/system.reflection.metadata.typereferencehandle?view=net-8.0
[2]: https://learn.microsoft.com/dotnet/api/system.reflection.metadata.typespecificationhandle?view=net-8.0
[3]: https://learn.microsoft.com/dotnet/api/system.reflection.metadata.handlekind?view=net-8.0