Support for multiple PUSH_END causes

[thomshutt]

This also brings in the creation of a StreamCache wrapper object from #30

[codecov]

Codecov Report

Merging #39 (3248607) into main (1c3a78e) will increase coverage by 10.01717%.
The diff coverage is 72.00000%.

@@                 Coverage Diff                  @@
##                main         #39          +/-   ##
====================================================
+ Coverage   42.65842%   52.67559%   +10.01717%     
====================================================
  Files             12          13           +1     
  Lines            647         598          -49     
====================================================
+ Hits             276         315          +39     
+ Misses           332         244          -88     
  Partials          39          39                  

Impacted Files	Coverage Δ
clients/callback_client.go	63.06306% <ø> (ø)
handlers/transcode.go	44.44444% <0.00000%> (ø)
cache/transcoding.go	45.71429% <45.71429%> (ø)
handlers/upload.go	51.28205% <91.66667%> (+6.35450%)	⬆️
api/http.go	55.88235% <100.00000%> (-1.26051%)	⬇️
cache/segmenting.go	100.00000% <100.00000%> (ø)
cache/stream.go	100.00000% <100.00000%> (ø)
handlers/misttriggers/triggers.go

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Impacted Files	Coverage Δ
clients/callback_client.go	63.06306% <ø> (ø)
handlers/transcode.go	44.44444% <0.00000%> (ø)
cache/transcoding.go	45.71429% <45.71429%> (ø)
handlers/upload.go	51.28205% <91.66667%> (+6.35450%)	⬆️
api/http.go	55.88235% <100.00000%> (-1.26051%)	⬇️
cache/segmenting.go	100.00000% <100.00000%> (ø)
cache/stream.go	100.00000% <100.00000%> (ø)
handlers/misttriggers/triggers.go