[inference] support sglang backend (#7278)

* Mimic SGLang offline Engine

* Add more tests and args

* Pass all current tests

* Clean Code

* fix sample_params

* clean code

* Fix Stream Chat

* change sglang from engine mode to server mode

* fix

* Fix Review Issues

* Use SGLang Built-In Utilities

* Fix test SGLang

* Some Doc Issue

* fix sglang engine

* add readme

---------

Co-authored-by: Jin Pan <jpan236@wisc.edu>
Co-authored-by: hiyouga <hiyouga@buaa.edu.cn>

setup.py

@@ -54,6 +54,7 @@ extra_require = {
     "awq": ["autoawq"],
     "aqlm": ["aqlm[gpu]>=1.1.0"],
     "vllm": ["vllm>=0.4.3,<=0.7.3"],
+    "sglang": ["sglang>=0.4.4"],
     "galore": ["galore-torch"],
     "apollo": ["apollo-torch"],
     "badam": ["badam>=1.2.1"],