more AssemblyNameInfo support in System.Reflection.Metadata

[KalleOlaviNiemitalo]

When I was adapting my code to the ILVerification breaking change dotnet/docs#41786 in .NET 9, I was a bit surprised that the following API does not exist yet. I'm posting this as a discussion for now because this doesn't explain the use scenarios yet.

 namespace System.Reflection.Metadata
 {
     public readonly partial struct AssemblyDefinition
     {
         // existing API
         public System.Reflection.AssemblyName GetAssemblyName();

+        // new API
+        public System.Reflection.Metadata.AssemblyNameInfo GetAssemblyNameInfo();
     }

     public readonly partial struct AssemblyReference
     {
         // existing API
         public System.Reflection.AssemblyName GetAssemblyName();

+        // new API
+        public System.Reflection.Metadata.AssemblyNameInfo GetAssemblyNameInfo();
     }
 }

Difficulties in implementing similar methods in application code:

• public static AssemblyNameInfo GetAssemblyNameInfo(this AssemblyReference assemblyReference) would have to call assemblyReference.GetAssemblyName(), which unnecessarily creates a CultureInfo instance. It cannot directly construct an AssemblyNameInfo from the public properties of AssemblyReference because translating StringHandle Name to a String requires a MetadataReader and there's no public way to read the MetadataReader _reader field of AssemblyReference.
• public static AssemblyNameInfo GetAssemblyNameInfo(MetadataReader reader, AssemblyReference assemblyReference) would have to translate AssemblyFlags to AssemblyNameFlags, which looks a bit complex for AssemblyFlags.WindowsRuntime, and for AssemblyFlags.PublicKey in AssemblyDefinition.

[KalleOlaviNiemitalo]

These APIs are now being proposed in #113749