Add DEVICE_LOCK permission to Shell to support ATS test

Adds DEVICE_LOCK permission to Shell to support the
CarDevicePolicyManagerTest. This permission is needed to call
DevicePolicyManager#lockNow  which locks the device.

Bug: 187199256
Test: atest CarDevicePolicyManagerTest
Merged-In: I3fa20b53b929c97a6760d65b432a74c3415d6a08
Change-Id: I3fa20b53b929c97a6760d65b432a74c3415d6a08