Switching to pure-rust mp3 decoder

[est31]

We should consider switching to a pure-rust mp3 decoder.

There seem to be two alternatives, puremp3 and Symphonia:

• https://github.com/pdeljanov/Symphonia
• https://github.com/Herschel/puremp3

We should study their quality as well as their speed to find out whether adoption is feasible.

[Shnatsel]

Sonata has been renamed to Symphonia, and the author considers the MP3 decoder complete. That should be worth a look.

My first impulse is to get a dataset of mp3 files from archive.org, run them through the decoder and compare results with a known-good implementation. minimp3 README mentions a conformance test suite, but I'm not sure how to obtain it.

[est31]

@Shnatsel sounds like a good approach!

[TonalidadeHidrica]

Seems that puremp3 is currently unmaintained.