Fix ActivityNotFoundException in ActivityScenario in API 33

[copybara-service[bot]]

Fix ActivityNotFoundException in ActivityScenario in API 33

There were two problems:

1. In AndroidManifest file, BootstrapActivity didn't have CATEGORY_LAUNCHER category which is now required for Intent.makeMainActivity.
2. When registering a broadcast receiver, you have to pass RECEIVER_EXPORTED flag in order to receive message from other processes.