The levels 5.2 and above were added in a newer FFmpeg version than OBS Studio is shipping with. Ideally we'd take these options directly from FFmpeg, but that is for a future commit.
Fixes the issue where "high444p" shows as "high", and "high" shows as "main", caused by the internal option mapping never being correct across version changes. Instead of keeping our own copy of things that has to be adjusted for each FFmpeg version, it's easier to just use the FFmpeg values and names.
* "Quality" Minimum/Maximum is actually QP Minimum/Maximum
* Bitrate Limits is now just Limits
* Buffer Size and Quality Target have been moved into "Limits".