wifi: Add new user restrictions

The new multi-user Wi-Fi design provides private networks for guest users.
However, guest users cannot add shared networks.
Conversely, HSU users, who log in to the network, should be restricted
from creating private networks. These different use cases need new user
restrictions.

Note: Currently, there is no use case which DPC (device policy controller)
need to change it dynamically. Currently those restriction
will be used as pre-restriction on specific user role (for example:
guest user should not allow to add / change shared user config)

Flag: android.multiuser.user_restriction_config_wifi_shared_private
Bug: 390240471
Test: TH & ABT for wifi mainline testing.
Change-Id: I97fefc41fd4f3f42250db9a7f99941cd6ccf0e23