Let advanced VPN profile visible immediately before the user consent to use VPN feature

- This CL will check whether advanced VPN apk is exist or not,
  and if so then show the preference of advanced VPN in the
  "Settings > Network & internet > VPN".

Bug: 239984274
Test: atest -c VpnSettingsTest
Change-Id: I8c11c7f2079d6ebec6c691b8bf2fb26dfc450663