Improve Transcode Quality

[leszko]

Improve Transcode Quality with:

• Always setting -preset slow -tier high
• Allowing setting CRF (CQ) to use constant rate factor instead of constant bitrate

Note that there will be a separate PR to change scale_cuda to scale_npp.

Related:

• Design Doc
• Linear Issue

[leszko]

CI is failing, but it's unrelated to this PR, failing also on master: https://github.com/livepeer/lpms/actions/runs/6022454830/job/16337223769?pr=372