Notification Minimalism Settings Main Switch

Add a main preference switch for the lockscreen
notification minimalism feature

Bug: 330387368
Bug: 354047572
Flag: com.android.server.notification.notification_minimalism
Test: atest
LockscreenNotificationMinimalismPreferenceControllerTest

Change-Id: I9aa4c51f9e316dd0dd1529d712b5e9486e43453b