Allow @testable elevation of access level for package decls

Author: elsh

lib/AST/Decl.cpp

@@ -4135,8 +4135,7 @@ AccessLevel ValueDecl::getEffectiveAccess() const {
   // Handle @testable/@_private(sourceFile:)
   switch (effectiveAccess) {
   case AccessLevel::Open:
-  case AccessLevel::Package: // Don't elevate package level with @testable
-    break;
+  case AccessLevel::Package:
   case AccessLevel::Public:
   case AccessLevel::Internal:
     if (getModuleContext()->isTestingEnabled() ||