* 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.
* Add cpu int4 example for BlueLM
* addexample optimize_model cpu for bluelm
* add example gpu int4 blueLM
* add example optimiza_model GPU for bluelm
* Fixing naming issues and BigDL package version.
* Fixing naming issues...
* Add BlueLM in README.md "Verified Models"