[vm] Enable new implementation of async/await in AOT mode

The new implementation results in a much smaller overhead of
async/await on AOT snapshot size. The savings depend on
how often async/await is used.

On a large Flutter app (customer: money)
AOT snapshot size -13.7% (arm64), -12.86% (arm)

Another large Flutter app
AOT snapshot size -8.69% (arm64).

Part 1 (kernel): https://dart-review.googlesource.com/c/sdk/+/241842
Part 2 (vm): https://dart-review.googlesource.com/c/sdk/+/242000

TEST=ci

Issue: #48378
Change-Id: Idf99bb98725a1ffb21a15b111f03f5461ed2c9d9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/242384
Reviewed-by: Siva Annamalai <asiva@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>

pkg/frontend_server/lib/frontend_server.dart

@@ -540,7 +540,7 @@ class FrontendCompiler implements CompilerInterface {
       nullSafety: compilerOptions.nnbdMode == NnbdMode.Strong,
       supportMirrors: options['support-mirrors'] ??
           !(options['aot'] || options['minimal-kernel']),
-      compactAsync: options['compact-async'] ?? false /*options['aot']*/,
+      compactAsync: options['compact-async'] ?? options['aot'],
     );
     if (compilerOptions.target == null) {
       print('Failed to create front-end target ${options['target']}.');

pkg/vm/lib/kernel_front_end.dart

@@ -202,7 +202,7 @@ Future<int> runCompiler(ArgResults options, String usage) async {
   final String? manifestFilename = options['manifest'];
   final String? dataDir = options['component-name'] ?? options['data-dir'];
   final bool? supportMirrors = options['support-mirrors'];
-  final bool compactAsync = options['compact-async'] ?? false /*aot*/;
+  final bool compactAsync = options['compact-async'] ?? aot;
 
   final bool minimalKernel = options['minimal-kernel'];
   final bool treeShakeWriteOnlyFields = options['tree-shake-write-only-fields'];