Add plasma-pa and bluedevil optional dependencies

The current selection of optional dependencies are somewhat arbitrary. 2 out of 6 (3 out of 6 in Plasma 6) are for input method support, packagekit-qt* for KRunner yet lacking common functionality like volume and bluetooth applet.

Consider gnome-shell, which is somewhat a counterpart to plasma-desktop for being a minimal installation of GNOME, has optional dependencies with more variety and usefulness.

Adding plasma-pa and bluedevil to optional dependencies would be a nice addition besides consulting the existing plasma group and plasma-meta package.