Offer mutliple wasm builds depending on media content

[KingSora]

Is your feature request related to a problem? Please describe.

The wasm file is very big because all of the decoding libraries are in there. In our case we are using ffmpeg solely for audio content. I was thinking maybe its a good idea to offer different wasm builds: full, video, audio, image.

Describe the solution you'd like

Offer different wasm builds which fit for certain usecases:

• full the same wasm build as of right now with everything in there
• video a wasm build which only has libraries which can be used for video content
• audio a wasm build which only has libraries which can be used for audio content
• image a wasm build which only has libraries which can be used for image content

Describe alternatives you've considered

I didn't consider any alternatives besides searching for smaller libraries than ffmpeg.wasm

[KingSora]

@lucasgelfond @rina-rgb sorry for tagging you directly, but I would be interested in contributing this feature but I'm not sure where to start.. can you give me a rough direction? :)