Shortcuts: Mark intents that are being requested from GB's App Picker
This allows us to filter out certain shortcuts (GB Actions) that should
exclusively be used within GravityBox only.
In this commit, Media Controls were made restricted. This means it won't
e.g. be possible to create launcher shortcuts for media controls. They
can be used within GB specific features only (e.g. ring targets, navbar
app launcher)
Mute media control action logging
GB Actions: shortcut to kill foreground app (available within GB only)