Move Lock panel into new Screen Panel and add Screen Privacy section to show Privacy screen toggle
The lock panel should be moved into a more generic screen panel as as per this design, so rename it and move the Screen Lock into a category.
This creates room to add a Screen Privacy section to support hardware with such capabilities.
The privacy screen toggle is visible only when there's a monitor that supports it and it's modifiable only when there's not hardware lock.
Requires: gsettings-desktop-schemas!49 (merged)
Works with: mutter!1952 (merged)
When privacy screen is not available:
Fixes: #909 (closed)
Edited by Marco Trevisan