Also applies sanitizing to prflx candidates, not just local ones. Also add tests for the port allocator Sanitize function. Bug: chromium:1218346 Change-Id: Ifbc7843cd6e289c09ca72b6ec610a34bbbf7e04e Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/222581 Reviewed-by: Henrik Boström <hbos@webrtc.org> Commit-Queue: Harald Alvestrand <hta@webrtc.org> Cr-Commit-Position: refs/heads/master@{#34292}