Add ProRes video encoder to encoding options for Save VIdeo

[raisindetre]

Motivation
I use standard quality lossless ProRes 422 in an editing workflow and it would be useful to be able to export out using this format.

Description
Display ProRes encoder in "Save Video" encoder drop-downs. Ideally conditional on a check for availability of a compatible ProRes encoding library in ffmpeg - "prores_aw" (Apple) or "prores_ks" (Kostya)

Suitable default ffmpeg flags would be
ffmpeg -i [input] -map 0:v:0 -c:v prores_ks -profile:v 2 -r [framerate] -pix_fmt -pix_fmt yuv422p10le [output_file].mov

Colorspace settings could be added by a knowlesdgable user in the "Additional parameters" box. For example:
-colorspace:v bt709 -color_primaries:v bt709 -color_trc:v bt709 -color_range:v tv

Ideally, if flags are defined in the "Additional parameters" box which are already present in the base ffmpeg command, these should be subsituted into the command. This preserves UX for standard users, but enables advanced users to set different parameters (e.g. set -profile:v 0 for proxy quality encoding or -profile:v 3 for HQ).

Alternatives
The current workaround is to export as lossless images and manually encode to ProRes with a separate command which is definitely workable but would be nice to have a video option built-in to save the extra handling.

Relates to: #2151