Settings: Add settings for MountService prefs and bump DB version to 46

Adds 4 new Settings:
    Secure.MOUNT_PLAY_NOTIFICATION_SND - Play notification sound on events
    Secure.MOUNT_UMS_AUTOSTART         - Auto-start UMS when host detected
    Secure.MOUNT_UMS_PROMPT            - Show notification when host detected
    Secure.MOUNT_UMS_NOTIFY_ENABLED    - Show notification while UMS enabled

These settings are also added to the Settings backup list

Signed-off-by: San Mehat <san@google.com>