[Sema] Inject implicit ParenExpr for unresolved member chains

In order to give unresolved member chain result types visibility in the AST, we inject an implicit ParenExpr in CSGen that lives only for the duration of type checking, and gets removed during solution application.

lib/Sema/CSSimplify.cpp

@@ -4306,6 +4306,9 @@ bool ConstraintSystem::repairFailures(
     break;
   }
 
+  case ConstraintLocator::RValueAdjustment:
+    return true;
+
   case ConstraintLocator::UnresolvedMemberChainResult: {
     if (repairViaOptionalUnwrap(*this, lhs, rhs, matchKind, conversionsOrFixes,
                                 locator))