Improve overall exception handling and error feedback to the user

The main goals of this patch are to:
- Improve the exception handling in Aegis and the way we present errors messages
  to the user when they occur.
- Write exception stack traces to the log in more places, so that the ADB logs
  we ask for from our users when reporting bugs become more useful.
- Reduce the amount of times we throw a RuntimeException, particularly when an
  Android Keystore operation fails.

Achieving the above goals ended up resulting in a very large refactor. The
intro and unlock flow of the app need to be retested entirely.

app/src/main/java/com/beemdevelopment/aegis/ui/AegisActivity.java

@@ -149,7 +149,7 @@ public abstract class AegisActivity extends AppCompatActivity implements AegisAp
      * the vault was locked by an external trigger while the Activity was still open.
      */
     private boolean isOrphan() {
-        return !(this instanceof MainActivity) && _app.getVaultManager().isLocked();
+        return !(this instanceof MainActivity) && _app.isVaultLocked();
     }
 
     private void setGlobalAnimationDurationScale() {