Add queue_name() to the TaskQueueBase interface

Add a queue_name() getter to the TaskQueueBase interface to allow
retrieval of the name assigned to a task queue. The getter returns an
absl::string_view and by default will return value of "unnamed".

Update the platform-specific TaskQueue implementations, refactor
SimulatedTaskQueue to use std::string, update MockTaskQueueBase and
various other test implementations.

Bug: webrtc:500769400
Change-Id: I93d4cb3b48ba47f340fee1b2cec2c02767e3fcf0
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/462523
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#47372}