[WIP] [Proposal] Rename stream submodules to improve readability

[peaBerberian]

While working on the Stream (the module and submodules determining which segments need to be loaded), I thought that the current architecture was relatively difficult to follow. For example, the submodules inside it are hierarchical and follow a StreamOrchestrator > PeriodStream > AdaptationStream > RepresentationStream path.

It makes relative sense when you know DASH and think a little about it, but I feel that it could be improved on.

For now, I'm not set on what we could name it, I just searched-and-replaced and tried different things.
Notably, directories inside src/core/stream are now numbered and indicates what job they have:

1-Period_selection/
2-Track_selection/   
3-Representation_selection/
4-Segment_selection/

(instead of orchestrator/, period/, adaptation/ and representation/ respectively)

And the modules themselves have also been renamed for what they do (e.g. TrackSelector) instead of the DASH abstraction level they're at like before (like PeriodStream). But I'm still not 100% happy with that.

This is background work not important for the other work I was doing (which is implementing more resilience on decoding errors) but it is something I saw so I thought I would open a PR so we can think about how we could improve on this.

[github-actions]

✅ Automated performance checks have passed on commit 3462b5ea13f07c28b91e7f2f1d92ec1a2ef1b372 with the base branch unit-tests.

Details

Performance tests 1st run output

No significative change in performance for tests:

Name	Mean	Median
loading	23.96ms -> 24.24ms (-0.271ms, z: 0.39638)	34.20ms -> 34.20ms
seeking	496.94ms -> 479.12ms (17.818ms, z: 0.16928)	1513.35ms -> 1513.65ms
audio-track-reload	30.45ms -> 30.45ms (0.004ms, z: 0.54886)	45.30ms -> 45.30ms
cold loading multithread	49.06ms -> 49.18ms (-0.121ms, z: 12.87448)	72.60ms -> 71.55ms
seeking multithread	50.41ms -> 38.99ms (11.423ms, z: 1.63793)	18.00ms -> 18.00ms
audio-track-reload multithread	28.65ms -> 28.75ms (-0.102ms, z: 1.08275)	42.30ms -> 42.15ms
hot loading multithread	18.69ms -> 18.82ms (-0.128ms, z: 4.24912)	27.60ms -> 27.30ms

[github-actions]

✅ Automated performance checks have passed on commit 3f4be023f584988bb9c6ec0df4e8bf4bcdd86291 with the base branch unit-tests.

Details

Performance tests 1st run output

No significative change in performance for tests:

Name	Mean	Median
loading	24.69ms -> 24.79ms (-0.102ms, z: 1.32758)	35.10ms -> 34.95ms
seeking	441.65ms -> 444.88ms (-3.233ms, z: 0.04873)	1515.75ms -> 1515.30ms
audio-track-reload	31.12ms -> 31.16ms (-0.035ms, z: 0.55678)	46.35ms -> 46.35ms
cold loading multithread	50.32ms -> 50.05ms (0.279ms, z: 12.27503)	74.25ms -> 73.05ms
seeking multithread	42.25ms -> 47.66ms (-5.414ms, z: 0.44458)	18.90ms -> 18.90ms
audio-track-reload multithread	29.59ms -> 29.37ms (0.225ms, z: 2.49557)	43.35ms -> 43.20ms
hot loading multithread	19.40ms -> 19.29ms (0.115ms, z: 4.45826)	28.35ms -> 28.05ms