Integrated crash monitor

Strongly related to: https://github.com/MuntashirAkon/AppManager/issues/34#issuecomment-657995859

A feature that would IMHO fit AM would be crash monitor functionality that would work in the following way:

- AM keeps a service in the bg/with broadcast receivers monitoring for app crashes
- When any app crashes, AM posts a notification "X has crashed" and lets the user view the stack trace and copy/save it
- AM would also provide a "past crashes" browser.

Additional features for monitoring crashes:
- Blacklist/whitelist
- Automatically restart crashed apps?
- Automatically tell when crashes are caused by disabling tracking components?

This feature is inspired by an Xposed module called Scoop that does the exact same thing.