* lazy model import in mlx_lm
* change lora loading
* fix olmo lora
* remove a bunch of unused stuff from plamo
* move phixtral to mlx-lm and out of llms/
A new argument "--max_seq_length" has been added to the command-line parser and passed as a parameter to the main function of the lora.py script. This allows users to specify and control the maximum sequence length during training.
* LoRA: Remove unnecessary model type judgments
1. Supported models are already checked in the load_model function in utils, no need to repeat the check in lora
2. The checks in lora are not synchronized with those in utils
* LoRA: add LoRA supported models in mlx_lm utils
