Revert "fdo#77683 the color in the toolbar buttons doesn't change."

This reverts commit f5dc536eae7dc28e09112ab9dd69e55fae015ee8.

This commit actually created a regression. A split button supposed
to show the last used color, not the current one.

I'll try to solve fdo#77683 in a different way, in a following commit.

Change-Id: I5df1ce49995e4755f54af977ca25d4e4dfdee629
Use transparent color directly

Change-Id: I47693666b3dd218eb8a74b936038c9169b054af1
Keep only one class for toolbox color controls

instead of 5 (mostly identical) classes.

Also the following bugs were fixed:

* All pickers now use split buttons. (fdo#45671)
* Color palette now indicates the current color. (fdo#73891)
  (Previous changes related to that bug are reverted as part
  of this commit.)
* Selecting a color from a float panel now updates the
  button. (fdo#77683)
* For Font color/background color in Writer, the color
  that is shown on the button, is always the one that's
  actually used. (Can be a different color after hiding
  the toolbar.)
* For Font color/background color in Writer, the button
  now indicates when we're in the format paintbrush mode.
  (Removed in 085e8a07e61ef2d3a82e11094d8773ab17cfdb3c
  for some reason.)

Change-Id: Idb4829552240c52fb0882aca627c8177bbe2f839