Add developer option for screenshare protections

Add developer option that allows disabling screenshare protections to
allow for better bug reports and debugging.

Bug: 320757744
Bug: 316955558
Bug: 316954829
Flag: ACONFIG com.android.server.notification.sensitive_notification_app_protection DISABLED
Flag: ACONFIG com.android.server.notification.screenshare_notification_hiding DISABLED
Test: atest SensitiveContentProtectionPreferenceControllerTest
Change-Id: Ibcb9f886aa599fe2442e755653c49f44cfa1830f