[ddc] Add async_patch support code for new async transform.

These added classes all support the state machine created by the async transform. They are largely copied from dart2js's async_patch with some notable differences:
- Calls to addAsyncCallback and removeAsyncCallback are added at key points to ensure async tests don't hang. This is especially relevant for tests where main is "async" but there are no awaits.
- There is some extra logic to support hot restart. For now this just ensures tests pass by making sure (add/remove)AsyncCallback is invoked the correct number of times. In the future we might want to avoid re-entering user code after a hot restart has occurred.
- DDC equivalents of error wrapping/unwrapping are used.

To make review easier I've added the new code in this separate change. A cleanup CL of the old code will follow. There will be a small commit range where the SDK has both but I'll submit them close to each other so that no one is likely to get one change but not the other.

Change-Id: I89cf3644c7f5f0ecf22499d62f46aca2951af6a9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/374443
Reviewed-by: Nicholas Shahan <nshahan@google.com>
Reviewed-by: Mark Zhou <markzipan@google.com>