Add more IceCandidatePairType for host-host CandidatePair

This is to help to differentiate endpoints which are behind NAT or on the public internet.

BUG=520101
R=pthatcher@webrtc.org

Review URL: https://codereview.webrtc.org/1328453003 .

Cr-Commit-Position: refs/heads/master@{#9864}
3 files changed