Improve jitterbuffer performance and de-duplicate code

[Sean-Der]

This PR removes the PriorityQueue and instead uses the rtpbuffer that was originally used by NACKs.

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 50 lines in your changes missing coverage. Please review.

Project coverage is 68.94%. Comparing base (0eab188) to head (60a8329).

Files with missing lines	Patch %	Lines
internal/rtpbuffer/rtpbuffer.go	58.20%	22 Missing and 6 partials ⚠️
internal/rtpbuffer/retainable_packet.go	61.29%	10 Missing and 2 partials ⚠️
pkg/jitterbuffer/jitter_buffer.go	85.71%	2 Missing and 2 partials ⚠️
internal/rtpbuffer/packet_factory.go	62.50%	3 Missing ⚠️
pkg/jitterbuffer/receiver_interceptor.go	50.00%	2 Missing ⚠️
pkg/nack/receive_log.go	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #279      +/-   ##
==========================================
- Coverage   72.98%   68.94%   -4.04%     
==========================================
  Files          79       79              
  Lines        3679     3571     -108     
==========================================
- Hits         2685     2462     -223     
- Misses        863      966     +103     
- Partials      131      143      +12     

Flag	Coverage Δ
go	?
wasm	68.94% <66.66%> (-2.06%)	⬇️

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