Feature Request: add argument to change encoder and preset used by ffmpeg

[TheHllm]

Being able to run for example:

isisdl --compress --encoder=hevc_nvenc --preset=fast

would make it easy to make use of hardware acceleration with out isisdl having to probe for supported encoders etc.

[Emily3403]

That is absolutely doable and I'll get that into the 1.4 update. Thanks for the suggestion 😊