Add support for Audio

[EriKWDev]

I have never worked with Audio and FFmpeg and have no idea how to structure audio data and pipe it to the ffmpeg-subprocess, but it would be really neat if we could play audio and have it sync with the animations.

[EriKWDev]

of interest..?
https://github.com/ManimCommunity/manim/blob/2d98af0b2229e37cecb4a0604335d1e911c3ff9f/manim/scene/scene_file_writer.py#L241

and here the FFmpeg commands:
https://github.com/ManimCommunity/manim/blob/2d98af0b2229e37cecb4a0604335d1e911c3ff9f/manim/scene/scene_file_writer.py#L603