Bug reporter improvements

[ZacSweers]

Some misc ideas:

• load available tags from repo (via graphql) into a spinner
• make description multiline up to 4, title up to 2
• would be neat if we could show progress percentage in image uploads. Not sure how to listen on multipart uploads.
• store last GitHub username in shared prefs, autofill next time
• specify current action in notification, update when it switches (i.e. uploading image -> creating issue)

[ZacSweers]

Another idea - add "private" option that reports to Bugsnag instead and just links the bugsnag report from the issue (or don't even make an issue).

This could be really useful to record network response data for bugs