Create KDED service to handle global shortcuts and OSDs

Bharadwaj Rajurequested to merge
work/bharadwaj/move-shortcuts-to-kded into master

New KDED service which handles global shortcuts and OSDs, called "audioshortcutsservice". Now these functions don't depend on an applet existing.

See plasma-desktop#113

BUG: 391578

Merge request reports