* support dora finetune
* solve problems in lora.py and tuner.utils.py
* add use_dora (bool) in functions of load adapters
* delete all unsupported quantization code and fix all the calculate problems in mlx_lm/tuner/dora.py
* Using stop_gradient to prevent gradients from flowing through ‘norm’ during backpropagation
* set DEFAULT_USE_DORA in mlx_lm/generate.py
* add annotation for all the use_dora
* mlx_lm/fuse.py support fuse dora layers and fix a bug of to_linear() in mlx_lm/tuner/dora.py
* simplify code of juding type of a fused layer in mlx_lm/fuse.py
* add use_dora in mlx_lm/fuse.py when apply_lora_layers()
* style + nits
* style + nits
* more updates
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Co-authored-by: chenyifei08 <chenyifei08@baidu.com>
Co-authored-by: Awni Hannun <awni@apple.com>
