Tweak options of tquic tools

[iyangsj]

• group different options by category and prioritize commonly used options
• rename max_requests_per_thread to total_requests_per_thread
• update description of some options

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.72%. Comparing base (898605c) to head (afba2b5).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #252 +/- ## =========================================== - Coverage 95.15% 94.72% -0.43% =========================================== Files 49 49 Lines 33181 33181 =========================================== - Hits 31572 31431 -141 - Misses 1609 1750 +141 ```

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