Add a toggle for enabling/disabling sensitive lockscreen notifications for Private Space

This adds a toggle in the Private Space Settings page to control the
lockscreen sensitive notifications for the private profile.
Sensitive notifications for private profile will still be disabled if
sensitive notifications are disabled for the main user.

Demo link:https://drive.google.com/file/d/1--LNXziTRTMvfdsJZAh90SiNiPxWNcI8/view?usp=sharing

Bug: 317067050
Test: atest SettingsUnitTests:HidePrivateSpaceSensitiveNotificationsControllerTest

Change-Id: Ie7f18c1a940e5ffd64112a01c48ac9dee58cb1ab