Enhancement: Hardware keyboard support

Navigation via hardware keyboard has been improved so that now focus order has a logical path, every element
is reachable and there are no traps. These improvements have been applied in main file list, spaces list,
drawer menu, share view and image preview.

https://github.com/owncloud/android/pull/4438
https://github.com/owncloud/android/issues/4366
https://github.com/owncloud/android/issues/4367
https://github.com/owncloud/android/issues/4368
