Feature/resource refactor

[lukeweston1234]

A bit of cleanup for shared resources. We now have the following system:

• Internal shared resources are on a flat, "before-realtime" heap allocated array
• Delay lines, loopers, etc. use a slice of this array. It is not owned, it is a window into the slice to avoid lifetime polution
• External samples are a bit more generalized, to a flat Arc<[f32]>, this generalizes a bit better for things like granular synths, wavetables, LUT, etc. Basically anything externally loaded.

Additionally, the flat, more cache friendly structure say a -47% runtime change on the basic stereo delay ;)

This was done for performance, and to prepare the way for various LUT, Granular demos, etc.

Basic stereo delay time: [14.971 µs 14.988 µs 15.006 µs]
change: [-47.528% -47.264% -46.990%] (p = 0.00 < 0.05)
Performance has improved.
Found 6 outliers among 100 measurements (6.00%)
2 (2.00%) low severe
1 (1.00%) low mild
1 (1.00%) high mild
2 (2.00%) high severe