[Sema] initial overhaul of isNoncopyable

This implementation has the function execute a request to scan the
inheritance clause of non-protocol nominals for a `~Copyable`. For
protocols, we look in the requirement signature.

This isn't our final state, as the GenericEnvironment needs to be
queried in general to determine of a Type is noncopyable. So for now
checking for a `~Copyable` only makes sense for Decls.

lib/AST/ProtocolConformance.cpp

@@ -1211,6 +1211,9 @@ static SmallVector<ProtocolConformance *, 2> findSynthesizedConformances(
   // Concrete types may synthesize some conformances
   if (!isa<ProtocolDecl>(nominal)) {
     trySynthesize(KnownProtocolKind::Sendable);
+
+    if (nominal->getASTContext().LangOpts.hasFeature(Feature::NoncopyableGenerics))
+      trySynthesize(KnownProtocolKind::Copyable);
   }
 
   /// Distributed actors can synthesize Encodable/Decodable, so look for those