[android] Soft keyboard fixes
1. Manually request focus for input fields and show keyboard This is needed when targetting API 28 which doesn't give focus anymore automatically like it used to be. Closes #1505 2. Remember keyboard states across screen rotations This also upgrades the emoji library and gets rid of the KeyboardAwareLinearLayout that is still a relict from the time when we were using Signal's emoji implementation. 3. Move soft keyboard showing/hiding into UiUtils