Merge changes I3b16caad,Iaf5ea7ab,I09a94042,I69a39039,I35300309, ...

* changes:
  Let network requests see VPNs.
  Move constants into a new file.
  Make sure listen requests from VPN apps see their own networks
  Add a test for new UID checking code.
  Remove UID_RANGES_ADDED and REMOVED.
  Move VPN allowed UIDs into NetworkCapabilities.
  Pre-import to remove a conflict.