Different look for clipboard clearing and clipboard viewing buttons, when clipboard is empty

[opk12]

Is your feature request related to a problem? Please describe. I use the "clear clipboard" button to protect passwords and to not risk pasting the wrong thing. Sometimes I forget if I had pressed the button; and sometimes I am unsure whether the phone received a tap or a short scroll (the finger blocks my view). So I end up finding myself checking the clipboard unnecessarily.

Describe the solution you'd like If the clipboard is empty, the "clear clipboard" and the "view clipboard" buttons might have a slightly different look (gray? thin lines?) that tells that the button is not going to do a useful operation.

[Helium314]

Slightly adjusting background color like for incognito or autocorrect keys is simple (setToolbarButtonActivatedState), but keeping it synced to the clipboard history state is somewhat tricky...