Summary:
This shortcut is used by default on Windows and it's also nice to have global shortcuts
use the Meta key in general.

Test Plan:
- Log into a new user account or reset the ksmserver section in the Shortcuts KCM
- Hit {key Meta L} or {key ctrl alt L}
- Observe that both work

Reviewers: #plasma, #vdg, broulik, GB_2

Reviewed By: #vdg, GB_2

Subscribers: nicolasfella, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D20178