Make Settings B&R flow work for HSUM

Current flow blocks system packages to be backed up for non-system users, unless explicitly allowed. This change modifies that allow list to include settings package.
Since settings is crucial part of B&R flow, hence it needs appropriate testing to ensure this works in HSUM.

There are many categories of settings for which B&R happens - System, Secure, Global, Device Config (Screen Rotation Lock, Display Density), Locale (Languages, App Languages), Lock Settings (Lock Pattern Visible), Softap Config (Tethering related), Network Policies (SIM specific Data related settings), Wifi Config (wpa_supplicant.conf file) and other SIM specific settings. To cover all bases, we manually test modifying settings from each category and doing B&R to see if changes are reflected.

Bug: 259848616
Test:
	- Set 'auto_time_zone' and 'auto_time' Global settings both to 0 (Default is 1)
	- Set 'accessibility_display_inversion_enabled' and 'lock_screen_show_notifications' Secure settings to 1 and 0 respectively (opposite of default values)
	- Set 'screen_off_timeout' System setting to 60000 (Default value - 30000)
	- Modify settings under System -> Languages & Input -> Languages. Add more languages.
	- Set Screen Lock to be a pattern. Change Pattern settings to make to make pattern not visible (default is visible).
	- Change Hotspot settings (Different hotspot name/password)
	- Add different networks under Wifi.
	- Set Auto screen rotation (default has auto rotation disabled)
	- Set SIM specific settings (Set Roaming ON, Modify Data warning and limit setting).
	- Do backup after settings change.
	- Restore on a fresh install device and verify all the changes.

Change-Id: I53d3c6527903a600049dfb2376c7e140e1e55031