Add a new wifi protection level

Wifi mainline module needs some permissions which are currently only
granted to signature components. Since mainline modules are not going to
be signed with OEM's signature, we need a new protection level to grant
some of these permissions to the wifi mainline APK.

Bug: 142234604
Test: Verified that wifi can get INTERACT_ACROSS_USERS_FULL permission
Change-Id: I26b0edff62497b5e08c2f2f504b0cd5f950682ad