[Property Wrappers] Generalize a few property wrapper decl context

checks to check for type context instead of local context.

This generalization will help us implement property wrappers on
global variables, which should use the same approach of not adding
synthesized accessors to the AST and instead lazily visit them in
SILGen.

lib/AST/Decl.cpp

@@ -5957,7 +5957,7 @@ VarDecl *VarDecl::getPropertyWrapperProjectionVar() const {
 }
 
 void VarDecl::visitAuxiliaryDecls(llvm::function_ref<void(VarDecl *)> visit) const {
-  if (!getDeclContext()->isLocalContext())
+  if (getDeclContext()->isTypeContext())
     return;
 
   if (auto *backingVar = getPropertyWrapperBackingProperty())

lib/SIL/IR/SILDeclRef.cpp

@@ -488,7 +488,7 @@ IsSerialized_t SILDeclRef::isSerialized() const {
   // Stored property initializers are inlinable if the type is explicitly
   // marked as @frozen.
   if (isStoredPropertyInitializer() || (isPropertyWrapperBackingInitializer() &&
-      !d->getDeclContext()->isLocalContext())) {
+                                        d->getDeclContext()->isTypeContext())) {
     auto *nominal = cast<NominalTypeDecl>(d->getDeclContext());
     auto scope =
       nominal->getFormalAccessScope(/*useDC=*/nullptr,