Add privapp-permissions for wm.shell

The privileged flag was added to the
SUBSCRIBE_TO_KEYGUARD_LOCKED_STATE permission. This commit updates
the platform's privapp-permissions for the wm.shell package to
include this permission.

Bug: 380120712
Flag: android.security.subscribe_to_keyguard_locked_state_perm_priv_flag
Test: Manually verified device booted with permission flag update
Change-Id: I466da2e6af665d1f1e05e30ac9dd1b6672abe7ec