Model: Migrate backend detection to a separate function

Seemed out of place in the common load function. In addition, rename
the transformers utils signature which actually takes a directory
instead of a file.

Signed-off-by: kingbri <8082010+kingbri1@users.noreply.github.com>

common/transformers_utils.py

@@ -45,7 +45,7 @@ class HuggingFaceConfig(BaseModel):
     quantization_config: Optional[Dict] = None
 
     @classmethod
-    async def from_file(cls, model_directory: pathlib.Path):
+    async def from_directory(cls, model_directory: pathlib.Path):
         """Create an instance from a generation config file."""
 
         hf_config_path = model_directory / "config.json"