[Sema] Run effects checking after actor isolation checking.

Effects checking for `async` requires actor isolation to have been
computed. This change removes effects checking out of the contextualize
initializers request, because effects checking isn't needed for
secondary files. Instead, effects checking is done in the primary decl
checker after actor isolation checking.

Author: hborla

Diff for: lib/Sema/TypeCheckDeclPrimary.cpp

@@ -2894,6 +2894,13 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
         if (!PBD->getDeclContext()->isLocalContext()) {
           (void) PBD->getInitializerIsolation(i);
         }
+
+        // Effects checking for 'async' needs actor isolation to be computed.
+        // Always run effects checking after the actor isolation checker.
+        if (auto *initContext = PBD->getInitContext(i)) {
+          auto *init = PBD->getInit(i);
+          TypeChecker::checkInitializerEffects(initContext, init);
+        }
       }
     }
 

Diff for: lib/Sema/TypeCheckStorage.cpp

@@ -619,7 +619,6 @@ static void checkAndContextualizePatternBindingInit(PatternBindingDecl *binding,
   if (auto *initContext = binding->getInitContext(i)) {
     auto *init = binding->getInit(i);
     TypeChecker::contextualizeInitializer(initContext, init);
-    TypeChecker::checkInitializerEffects(initContext, init);
   }
 }