[wip] Implement reverse file reading

[obsoleszenz]

Addresses https://github.com/RustyDAW/creek/issues/14

Todo

• [x] Implement reverse reading in decode_symphonia
• [ ] Use it in core/caching logic
• [ ] rebase on main once https://github.com/RustyDAW/creek/pull/16 is merged

[Be-ing]

Could you add a reverse button to the demo player?

[obsoleszenz]

Could you add a reverse button to the demo player?

I guess yes but makes not too much sense without any functionality? ^^ I still didn't figure out the caching part :/

[abique]

From a naive perspective, I'd be interested in:

• telling how much cache I want before my current position
• telling how much cache I want after my current position
• Peek buffer at pos and then seek, or have a direction argument to read()

That way I can play forward/backward, implement scratching etc...