JitterBuffer: Improve performance for SampleBuilder use

[thatsnotright]

Description

This PR Should hopefully improve the performance for use by SampleBuilder and in the general case.

@at-wat If you have time would you be able to test this PR and the corresponding branch I created in the webrtc repository? https://github.com/pion/webrtc/pull/2959

Thank you!

[codecov[bot]]

Codecov Report

:x: Patch coverage is 83.50000% with 66 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 78.60%. Comparing base (3cb438f) to head (7e03435).

Files with missing lines	Patch %	Lines
pkg/jitterbuffer/rbtree.go	84.26%	45 Missing and 11 partials :warning:
pkg/jitterbuffer/jitter_buffer.go	61.53%	5 Missing :warning:
pkg/jitterbuffer/receiver_interceptor.go	80.00%	4 Missing and 1 partial :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #292      +/-   ##
==========================================
- Coverage   78.64%   78.60%   -0.04%     
==========================================
  Files          82       83       +1     
  Lines        5113     5497     +384     
==========================================
+ Hits         4021     4321     +300     
- Misses        921      995      +74     
- Partials      171      181      +10     

Flag	Coverage Δ
go	78.60% <83.50%> (-0.04%)	:arrow_down:
wasm	76.20% <83.50%> (+0.08%)	:arrow_up:

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[at-wat]

I'll try it later!

[at-wat]

@thatsnotright I tested this branch locally in my usecase and confirmed that SampleBuilder's performance is good! (mostly same CPU/memory usage as the latest release)

[thatsnotright]

@thatsnotright I tested this branch locally in my usecase and confirmed that SampleBuilder's performance is good! (mostly same CPU/memory usage as the latest release)

@at-wat Thank you for taking the time to test, I appreciate your time! I'll clean up the code a little and make some test coverage improvements and then work with @Sean-Der on next steps!

[at-wat]

@thatsnotright could you add a benchmark test and post a comparison between the master branch and this PR?