The QuicTransportChannel now creates outgoing QUIC streams
for sending a message, and incoming QUIC streams for
receiving a message. It also signals when the QUIC connection
closes.
Split from CL https://codereview.webrtc.org/1844803002/.
BUG=
Review URL: https://codereview.webrtc.org/1856513002
Cr-Commit-Position: refs/heads/master@{#12323}