* test support bitsandbytesconfig
* update style
* update cpu example
* update example
* update readme
* update unit test
* use bfloat16
* update logic
* use int4
* set defalut bnb_4bit_use_double_quant
* update
* update example
* update model.py
* update
* support lora example
* fix bf16 related issue
* fix
* update based on comment & add arc lora script
* update readme
* update based on comment
* update based on comment
* update
* force to bf16
* fix style
* move check input dtype into function
* update convert
* meet code review
* meet code review
* update merged model to support new training_mode api
* fix typo
* Set BIGDL_IMPORT_IPEX default to true, i.e., auto import IPEX for XPU.
* Remove import intel_extension_for_pytorch as ipex from GPU example.
* Add support for bigdl-core-xe-21.
* lora support and single card example
* support multi-card, refactor code
* fix model id and style
* remove torch patch, add two new class for bf16, update example
* fix style
* change to training_mode
* small fix
* add more info in help
* fixstyle, update readme
* fix ut
* fix ut
* Handling compatibility issues with default LoraConfig