Add adaptive trace buffer growth option

[akx]

This PR proposes --grow_on_overflow (with an optional --max_tracer_entries flag) to allow viztracer to grow the circular buffer as needed instead of dropping early events.

Warning

It's possible to utterly hose your machine's memory if you don't set --max_tracer_entries though. 😄

[codecov]

Codecov Report

❌ Patch coverage is 84.37500% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 99.76%. Comparing base (db53893) to head (f9e7d0b).

Files with missing lines	Patch %	Lines
src/viztracer/viztracer.py	85.18%	4 Missing ⚠️
src/viztracer/main.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##            master     #672      +/-   ##
===========================================
- Coverage   100.00%   99.76%   -0.24%     
===========================================
  Files           20       20              
  Lines         2473     2503      +30     
===========================================
+ Hits          2473     2497      +24     
- Misses           0        6       +6     

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