[Frontend] Swift 6: Enable checked continuations when suspending for an async ObjC calls

Enables `-checked-async-objc-bridging` flag by default starting
from swift 6 language mode to provide enhanced debugging and
runtime checking for the correct usage of continuations passed
in a call to ObjC from Swift.

(cherry picked from commit b5b4cba)

Author: xedin

lib/Frontend/CompilerInvocation.cpp

@@ -1569,6 +1569,8 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
                      A->getAsString(Args), A->getValue());
       HadError = true;
     }
+  } else if (Opts.isSwiftVersionAtLeast(6)) {
+    Opts.UseCheckedAsyncObjCBridging = true;
   }
 
   // @DebugDescription uses @_section and @_used attributes.

test/SILGen/objc_async_checked.swift

@@ -1,4 +1,5 @@
-// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -emit-silgen -checked-async-objc-bridging=on -I %S/Inputs/custom-modules  -disable-availability-checking %s -verify | %FileCheck --check-prefix=CHECK --check-prefix=CHECK-%target-cpu %s
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -emit-silgen -swift-version 6 -I %S/Inputs/custom-modules -disable-availability-checking %s -verify | %FileCheck --check-prefix=CHECK --check-prefix=CHECK-%target-cpu %s
+
 // REQUIRES: concurrency
 // REQUIRES: objc_interop
 

test/SILGen/objc_effectful_properties_checked.swift

@@ -1,4 +1,4 @@
-// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -emit-silgen -checked-async-objc-bridging=on -disable-availability-checking -I %S/Inputs/custom-modules %s -verify | %FileCheck --enable-var-scope --check-prefix=CHECK --check-prefix=CHECK-%target-cpu %s
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -emit-silgen -swift-version 6 -disable-availability-checking -I %S/Inputs/custom-modules %s -verify | %FileCheck --enable-var-scope --check-prefix=CHECK --check-prefix=CHECK-%target-cpu %s
 // REQUIRES: concurrency
 // REQUIRES: objc_interop