[Inference] First PR for rebuild colossal-infer (#5143)

* add engine and scheduler

* add dirs

---------

Co-authored-by: CjhHa1 <cjh18671720497outlook.com>

colossalai/inference/core/request_handler.py

@@ -0,0 +1,10 @@
+class RequestHandler:
+    def __init__(self, cache_config) -> None:
+        self.cache_config = cache_config
+        self._init_cache()
+
+    def _init_cache(self):
+        pass
+
+    def schedule(self, request):
+        pass