fix keyboard layout OSD on X

OSD for alternative shortcut has been removed in 9021b3cb,
because that approach don't work well with new layout applet.

New approach intends to make OSD behavior almost identical on X11/
Wayland - OSD should only pop up on keyboard shortcut and not on the
applet click/mouse wheeling.

Also, it implements OSD for the Main shortcut.

BUG: 408928
2 jobs for !491 with work/bam/OSD in 3 minutes and 3 seconds (queued for 65 minutes and 18 seconds)
latest merge request
Name Stage Failure
failed
suse_tumbleweed_qt515 Build
No job log
failed
freebsd_qt515 Build
No job log