Added messages for access control rejection messages

[ethouris]

This provides message strings for the extended reject reasons, including HTTP-adopted codes.

[codecov-commenter]

Codecov Report

Merging #2606 (f14c349) into master (41c4b1f) will increase coverage by 0.24%.
The diff coverage is 79.24%.

@@            Coverage Diff             @@
##           master    #2606      +/-   ##
==========================================
+ Coverage   66.46%   66.70%   +0.24%     
==========================================
  Files          99       99              
  Lines       19826    19875      +49     
==========================================
+ Hits        13177    13258      +81     
+ Misses       6649     6617      -32     

Impacted Files	Coverage Δ
srtcore/srt.h	100.00% <ø> (ø)
srtcore/srt_c_api.cpp	46.04% <67.64%> (+5.71%)	⬆️
srtcore/core.cpp	61.84% <100.00%> (+1.12%)	⬆️
test/test_listen_callback.cpp	91.59% <100.00%> (+2.70%)	⬆️
srtcore/api.cpp	53.22% <0.00%> (-1.76%)	⬇️
srtcore/buffer_snd.cpp	68.06% <0.00%> (-0.65%)	⬇️
srtcore/queue.cpp	80.73% <0.00%> (+0.29%)	⬆️
srtcore/congctl.cpp	82.90% <0.00%> (+0.51%)	⬆️
... and 5 more

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