[NFC] Thread DeclNameRef through most of the compiler

This huge commit contains as many of the mechanical changes as possible.

lib/Sema/DerivedConformanceRawRepresentable.cpp

@@ -110,7 +110,7 @@ deriveBodyRawRepresentable_raw(AbstractFunctionDecl *toRawDecl, void *) {
   for (auto elt : enumDecl->getAllElements()) {
     auto pat = new (C) EnumElementPattern(TypeLoc::withoutLoc(enumType),
                                           SourceLoc(), DeclNameLoc(),
-                                          DeclName(), elt, nullptr);
+                                          DeclNameRef(), elt, nullptr);
     pat->setImplicit();
 
     auto labelItem = CaseLabelItem(pat);