color chooser: Use a popover menu

Make the color chooser use a popover menu
and actions.
5 jobs for wip/matthiasc/context-menu in 15 minutes (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #325325
fedora-x86_64

00:06:21

passed #325326
win32
msys2-mingw32

00:14:57

 
  Flatpak
manual #325327
allowed to fail manual
flatpak-manual:demo
manual #325329
allowed to fail manual
flatpak-manual:icon-browser
manual #325328
allowed to fail manual
flatpak-manual:widget-factory