Add simulation tests

[mengelbart]

Description

This PR adds simulation tests for congestion control. It can be run with go test -tags=simulation ./simulation/ which creates log files for each test in ./simulation/logs. Some metrics can be extracted from the log files and plotted using the main.py script.

[codecov]

Codecov Report

❌ Patch coverage is 97.74011% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 99.06%. Comparing base (5de85f8) to head (d8c7f55).

Files with missing lines	Patch %	Lines
gcc/delay_rate_controller.go	95.91%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##              main      #37      +/-   ##
===========================================
- Coverage   100.00%   99.06%   -0.94%     
===========================================
  Files            7       10       +3     
  Lines          253      430     +177     
===========================================
+ Hits           253      426     +173     
- Misses           0        2       +2     
- Partials         0        2       +2     

Flag	Coverage Δ
go	99.06% <97.74%> (-0.94%)	⬇️

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