Description

The LifecycleWatcher usually takes care of starting / restarting and ending sessions.

But due to #2241 we also directly start a new session when the SDK is initialized, in order to have a session we can mark as crashed in the case of an early app start crash.

So usually the following happens:

1. the SDK is initialized and SentryAndroid.init starts the session
2. Later LifecycleWatcher receives the system callback, but no-ops because the session is already running.

Due to the "async" / deferred way RN initializes the SDK, 1. and 2. are swapped: First LifecycleWatcher immediately receives a system callback and starts the session and then the SDK init starts a second one.