[keyboard accessibility] No tabstops on many screen elements / focus is invisible

[yurivict]

I am not able to reach these items through the keyboard:

• user profile
• user status line
• user status all unreachable through the keyboard
• contact name unreachable, it should be focusable and up/down arrows should switch between users
• add friends/create a group chat/etc.... the rest of the elements at the bottom left unreachable
• send a screenshot unreachable

What is reachable:

• Search contacts
• Scrolling of the contacts list
• The message edit box
• Smileys/send file (but not "send screenshot")
• Send button
• Call buttons

Please make sure that every screen element is keyboard-accessible.

Additionally, when some screen element is reached through tabs it should always display the "focus box" so that it is obvious what is focused. Currently most of them don't indicate that they have focus.

[tox-user]

For some of those things we might also want to implement shortcuts.