Nat464Xlat: clat management cleanup
This patch does some minor refactoring of clat starting/stopping code:
- remove unused LinkProperties arguments in updateClat
- remove unused Context argument in Nat464Xlat ctor
- introduce ensureClatIsStarted and ensureClatIsStopped methods and
simplify updateClat
- add clatd to NetworkAgentInfo toString() method
- clarify some comments
This changes prepare for moving BaseNetworkObserver callbacks to
ConnectivityService.
Bug:
62997041
Bug:
64571917
Test: runtest frameworks-net
manually connected to IPv6 only network and went to test-ipv6.com
Change-Id: Idb204784614cfe700f73255a7a7b78c5e9ee6eca