This patch just refactors creation of P2P transport channel,
pushing down the IceTransportInit object rather than decomposing
it going down.
The IceTransportInit object will in subsequent patches be
extended with a field trial container.
Reason for splitting patch into this and subsequent is
to allow changes to internal factories.
Bug: webrtc:10335
Change-Id: Icc8b6e4142744b64d134bcb2d4a56777745db62b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/255602
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Jonas Oreland <jonaso@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36215}
7ddc7d548c