feat: mark patches good after delay

[eseidel]

Right now we mark a patch as "good" (successfully booted) after Dart_Init() completes. Which only verifies that we successfully read in the snapshot.

Thus if developer pushes a patch which crashes during startup (but after Dart_Init) we won't catch the crash.

We should instead either hook into a later callback (like first frame) or probably easier is to just wait a few seconds before we mark a patch as good.