Add entitlement check for usb tethering

Before this CL, usb tethering in detail page doesn't have entitlement
check. This CL fix it by using the correct API

Also polish it by updating the UI before entitlement check to align
hotspot page. So in UI it will first check "usb tethering". If
entitlement check fail, it will revoke and go back to previous selection.

Bug: 115707279
Test: RunSettingsRoboTests
Merged-In: I3d2ebad2879479a870bcdfe596bb88b83c424389
Change-Id: I3d2ebad2879479a870bcdfe596bb88b83c424389