Fix retransmitter bug

[hassanctech]

Issue #, if available: #1991, #1453

What was changed?

• Added a diagram to show the memory layout for the ReTransmitter struct.
• Fixed a bug where where an index for sequenceNumberList may go out of bounds but is hard to detect / won't cause a crash because in memory the next memory spot when we go out of bounds is into the validIndexList, and unless it's size is zero (which is likely never the case) we will not actually go out of bounds but instead we will overwrite a value in the wrong list.
• Fixed an issue where we are reading an index from one list but updating the value in a different list.

Why was it changed?

• Multiple reported customer issues, see at top.

How was it changed?
See What was changed section and the file diff.

What testing was done for the changes?
CI. [TODO] More targeted tests need to be added, will remove this once it has been added.

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.02%. Comparing base (8492287) to head (7e76675).

❗ Current head 7e76675 differs from pull request most recent head c972883

Please upload reports for the commit c972883 to get more accurate results.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1994      +/-   ##
===========================================
+ Coverage    88.80%   89.02%   +0.22%     
===========================================
  Files           48       48              
  Lines        12709    12710       +1     
===========================================
+ Hits         11286    11315      +29     
+ Misses        1423     1395      -28     

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