Add get-disabled shell command to locksettings

Added shell command that outputs whether the lock screen is disabled.

Test: Ran "adb shell locksettings get-disabled" while phone had lock
screen and when it did not.
Merged-In: I3532e41e2ee4770bd0801dd431fdbc884c2bafa4
Fixes: 64848695

Change-Id: I3532e41e2ee4770bd0801dd431fdbc884c2bafa4