feat: add MQTT benchmarking tool with io_uring support

[qzhuyan]

• Implemented a new benchmarking tool for MQTT using io_uring for efficient asynchronous I/O operations.
• Introduced worker threads for handling TCP and QUIC connections, with support for configurable client and message parameters.
• Added statistics tracking for sent messages, acknowledgments, errors, and connection states.
• Enhanced the MQTT client options to allow customization of the internal parser buffer size.
• Updated the MQTT engine to utilize the configurable parser buffer size for improved performance in high-connection scenarios.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 33.33333% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.83%. Comparing base (8e7bd2d) to head (f5d88bf).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/mqtt_client/opts.rs	20.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #100      +/-   ##
==========================================
- Coverage   76.90%   76.83%   -0.07%     
==========================================
  Files          66       66              
  Lines       17100    17105       +5     
==========================================
- Hits        13150    13143       -7     
- Misses       3950     3962      +12     

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