Fix uninitialized LogSink::min_severity_ and improve InitializeLogging

- Default min_severity_ to LS_INFO at declaration in LogSink to avoid uninitialized access.
- Add queue_name() getter to LogLineRef.
- Transfer log_queue_name, log_timestamp, log_to_stderr, and debug_severity in InitializeLogging.
- Update tests to verify changes.

Bug: None
Change-Id: Ie972b4c9a7f948e27b316b2127be4a53b0c35435
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/466980
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#47557}