Add the SNAC audio tokenizer. (#2869)

* Add the SNAC audio tokenizer.

* More snac.

* Again more snac.

* Add some example code for snac.

* Get the weights to load.

* Add to the snac model.

* Fixes.

* Get round-tripping to work.

* Save/load code files.

* Clippy fix.

* Fmt fix.

candle-transformers/src/models/mod.rs

@@ -104,6 +104,7 @@ pub mod rwkv_v6;
 pub mod segformer;
 pub mod segment_anything;
 pub mod siglip;
+pub mod snac;
 pub mod stable_diffusion;
 pub mod stable_lm;
 pub mod starcoder2;