Add parameter to force HW Session Reinit

[leszko]

Add a possibility to request HW Session Reinit by adding a transcode parameter:

{"forceSessionReinit":true}

The context for this change is that if the encoding or resolution of a segment has changed, then the HW session needs a restart. Otherwise, we see quality issues in all the following segments.

[codecov]

Codecov Report

Merging #2882 (b85dbcb) into master (fad5837) will decrease coverage by 0.03268%.
The diff coverage is 29.62963%.

@@                 Coverage Diff                 @@
##              master       #2882         +/-   ##
===================================================
- Coverage   56.40523%   56.37255%   -0.03268%     
===================================================
  Files             89          89                 
  Lines          19367       19380         +13     
===================================================
+ Hits           10924       10925          +1     
- Misses          7839        7849         +10     
- Partials         604         606          +2     

Files	Coverage Δ
server/broadcast.go	77.55776% <ø> (ø)
server/rpc.go	72.10682% <100.00000%> (+0.08301%)	⬆️
core/transcoder.go	34.45596% <0.00000%> (ø)
server/mediaserver.go	67.20183% <57.14286%> (-0.15449%)	⬇️
core/streamdata.go	48.27586% <0.00000%> (-0.84695%)	⬇️
core/lb.go	76.96629% <0.00000%> (-3.15067%)	⬇️

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Files	Coverage Δ
server/broadcast.go	77.55776% <ø> (ø)
server/rpc.go	72.10682% <100.00000%> (+0.08301%)	⬆️
core/transcoder.go	34.45596% <0.00000%> (ø)
server/mediaserver.go	67.20183% <57.14286%> (-0.15449%)	⬇️
core/streamdata.go	48.27586% <0.00000%> (-0.84695%)	⬇️
core/lb.go	76.96629% <0.00000%> (-3.15067%)	⬇️