Add E2E Test for RTX

[Sean-Der]

Assert that generation of NACKs and sending of RTX operates as expected.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.12%. Comparing base (32f7063) to head (8f16c48).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2919      +/-   ##
==========================================
- Coverage   79.22%   79.12%   -0.11%     
==========================================
  Files          89       89              
  Lines        8541     8541              
==========================================
- Hits         6767     6758       -9     
- Misses       1288     1296       +8     
- Partials      486      487       +1     

Flag	Coverage Δ
go	80.68% <ø> (-0.12%)	⬇️
wasm	64.92% <ø> (ø)

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