Wavesurfer as alternate audio player

Adds an alternative audio player which renders the waveform of the audio file (uses wavesurfer.js to do that)

pleroma themes do apply to it

the waveform isn't rendered right away since it needs the whole file to do that. in order to prevent it requesting as soon as it shows up, i made it so that it loads the file if you click play. the track will play right away while it loads the waveform for it

i doubt it will work on instances without media proxy (couldn't test that case) and it would need more work to make it more usable on mobile.
because of those reasons and of personal preference i made it opt-in

I already have this running on my instance and it seems to perform pretty well there