Make volume buttons take a photo

It is super helpful to use volume buttons on the phone when taking a selfie. Google camera does that and it would be great if Androidify did the same

Start by locating Androidify's selfie camera screen and the code that handles camera shutter actions or phone key events; no specific files or tests are named in the issue. Done means pressing either volume button while taking a selfie triggers the same photo capture as the on-screen shutter.

Written by the indexing model from the issue text.