Introduce explicit configuration for logging initialization

Introduce the LoggingConfig struct and InitializeLogging function to
eventually replace legacy static methods for configuring the logging
system. This centralizes logging parameters and sinks, ensuring a more
consistent, less error prone, more efficient (due to not relying on per
log message synchronization) initialization sequence.

The new model requires that configuration is applied only once. If
InitializeLogging is called after the system has already started—either
explicitly or implicitly via a log call—the function returns false and
the provided configuration is ignored. This prevents race conditions and
inconsistent logging states that can occur when modifying global log
settings during runtime, but allows for reduces synchronization at
runtime.

Key modifications:
- Deprecate LogMessage::LogThreads and LogMessage::ConfigureLogging.
- Remove LogPrefix and SetLogPrefix methods, centralizing prefix in
  config.
- Remove streams_empty_ as it is no longer needed.
- Include documentation for the new initialization flow.
- Start transitioning internal logging state management to use the
  unified configuration object instead of individual static flags.

Bug: webrtc:42234107
Change-Id: I1879e9626b7ede5d2a1ebf238c7f26c4f185e6b1
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/462063
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#47435}