Updates tab + misc UI improvements.

Does away with "My Apps", replacing instead with "Updates" (Fixes #840 (closed)). The things it doesn't address (fully) from #840 (closed) is offline "mark for install", security warnings, and donation prompts.

Other UI tweaks are:

  • Back button now works as expected (Fixes #876 (closed)) for:
    • Viewing list of apps in a category
    • Searching for apps
    • Viewing installed apps
    • Manage repositories
    • App Details
  • Bottom navigation bar uses new icons (Fixes #838 (closed)).
  • Bottom navigation now includes labels for each item (Fixes #892 (closed)).
  • Notification about available updates takes user to the main "Updates" tab.
  • Use rounded buttons instead of square ones (Identified in #840 (closed)).

There is one concern I have which should be addressed in a future MR (or this if you think so). That is the new service which scans the disk cache for downloaded apks, and then adds downloaded items to the AppUpdateStatusManager with a status of ReadyToInstall. This works great for the new "Updates" tab, but it now also continually shows the update notifications to the end user even if they have previously dismissed them. Is this okay, given we are only showing notifications for apps which are downloaded and ready to install, not those for which an update is available (which I'd think would get annoying if we kept notifying about that)?

For those wanting to see/test this (e.g. @crwinfrey), check out F-Droid.new-ui.unofficial.debug.apk.