Add SessionCreationInitiator metrics for Quic and Spdy

This CL adds new metrics to measure SessionCreationInitiator for Quic
and Spdy, for session to GWS. Since we want to record the creation
initiator for each session with at least one request (i.e. a session
that has been used at least once in order to avoid recording preconnects
which the connection was established was never used), we conduct the
following:

- Check how many streams we created for the session (preconnects do not
  request a stream)
- If we created more than one stream, we record the metric when
  destructing the session (following other metrics).

Bug: 372873699
Change-Id: I98e57fcbbd96b06b19e23d742b67a3dd192be718
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5992511


Reviewed-by: Kenichi Ishibashi <bashi@chromium.org>
Reviewed-by: Nidhi Jaju <nidhijaju@chromium.org>
Commit-Queue: Keita Suzuki <suzukikeita@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1378924}