Adds |disableIPV6| and |disableIPV6OnWiFi| properties to RTCConfiguration Bug: None Change-Id: Id59fb2002afadd7817f7caeaa62231bf90ecb274 Reviewed-on: https://webrtc-review.googlesource.com/c/109280 Commit-Queue: Anders Carlsson <andersc@webrtc.org> Reviewed-by: Anders Carlsson <andersc@webrtc.org> Cr-Commit-Position: refs/heads/master@{#25496}