Fix view component metadata serialization (#12494)

This should fix #12492 but I don't
know where to put it, or how to test it :P

Author: davidwengier

src/Compiler/Microsoft.CodeAnalysis.Razor.Compiler/src/Mvc/ViewComponentMetadata.cs

@@ -19,7 +19,7 @@ internal ViewComponentMetadata(string name, TypeNameObject originalTypeNameObjec
     public string Name { get; }
     internal TypeNameObject OriginalTypeNameObject { get; }
 
-    public string OriginalTypeName => OriginalTypeNameObject.FullName.AssumeNotNull();
+    public string? OriginalTypeName => OriginalTypeNameObject.FullName;
 
     internal override bool HasDefaultValue => false;
 
@@ -31,9 +31,9 @@ private protected override void BuildChecksum(in Checksum.Builder builder)
     public ref struct Builder
     {
         public string? Name { get; set; }
-        internal TypeNameObject? OriginalTypeNameObject { get; set; }
+        internal TypeNameObject OriginalTypeNameObject { get; set; }
 
         public readonly ViewComponentMetadata Build()
-            => new(Name.AssumeNotNull(), OriginalTypeNameObject.AssumeNotNull());
+            => new(Name.AssumeNotNull(), OriginalTypeNameObject);
     }
 }