Replace GCC and deprecate gcc and cc packages

[mengelbart]

Description

This change replaces the GCC implementation with the improved version from pion/bwe. Since bandwidth estimation can be done without interceptors, the implementation no longer needs to be closely coupled with them as it was in the past.

This is a draft until pion/bwe#2 is merged and a bwe tag is released.

[codecov]

Codecov Report

❌ Patch coverage is 35.29412% with 33 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.92%. Comparing base (35588b3) to head (5e399ab).

Files with missing lines	Patch %	Lines
pkg/gcc/send_side_bwe.go	42.85%	22 Missing and 2 partials ⚠️
pkg/cc/interceptor.go	0.00%	9 Missing ⚠️

❌ Your patch check has failed because the patch coverage (35.29%) is below the target coverage (70.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #401      +/-   ##
==========================================
- Coverage   79.87%   78.92%   -0.96%     
==========================================
  Files          88       75      -13     
  Lines        4581     4061     -520     
==========================================
- Hits         3659     3205     -454     
+ Misses        739      683      -56     
+ Partials      183      173      -10     

Flag	Coverage Δ
go	78.92% <35.29%> (-0.96%)	⬇️

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