applets/lock_logout: add logout screen option
Reason for the change
With the change to simplify the logout greeter UI when invoked with a specific option, there is currently no option to trigger the logout greeter with all of the options via any existing actions.
This adds a logout screen action which shows the logout greeter with available options.
Test plan
Enable the option and click the logout screen button -> be presented with the logout greeter with multiple available options.
Screenshots or screen recordings
Bugs fixed
Edited by Thomas Carmichael