Have BaseCrashReportDialog extend FragmentActivity

[str4d]

In Briar's crash report and feedback activity, we were considering using fragments to improve the crash UX for users. However, FragmentActivity has no delegate alternative (unlike AppCompatActivity, which we can replicate in our subclass of BaseCrashReportDialog using AppCompatDelegate), and because ACRA only accepts subclasses of BaseCrashReportDialog, it is currently not possible to use fragments with ACRA.

The easiest and IMHO best solution is to simply change BaseCrashReportDialog to extend FragmentActivity instead of Activity. This is a one-line change (plus import), should have zero effect on existing usages, and does not require any additional dependencies (because FragmentActivity is part of support-v4, which is already leveraged by ACRA).

[str4d]

Note that it is possible to do something similar by using FrameLayout and showing/hiding a series of views (like used to be commonly done before fragments were introduced), but that is messier to implement, and requires more work to handle transitions between views.

[william-ferguson-au]

Happy to review a pull request.

[william-ferguson-au]

Closed with merge of #488