feat: Extend ListenerInterface and BlockingCounter

[dranikpg]

• Allow traversing connection on the current thread. Goal: Track clients that are currently dispatching when performing changes on some thread
• There is a need for BlockingCounter->WaitWithTimeout(), but I'm not sure how to easily implement timeouts for it. So instead poll the current state with IsReady() Goal: This allows polling from a single fiber, instead of starting another fiber that cancels the counter after a timeout

[codecov-commenter]

Codecov Report

Attention: 9 lines in your changes are missing coverage. Please review.

Comparison is base (88514b9) 77.48% compared to head (920df81) 77.33%.

Files	Patch %	Lines
util/fibers/listener_interface.cc	0.00%	9 Missing :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #171 +/- ## ========================================== - Coverage 77.48% 77.33% -0.15% ========================================== Files 98 98 Lines 7221 7228 +7 ========================================== - Hits 5595 5590 -5 - Misses 1626 1638 +12 ```

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