YOLOX support for OpenVINO Detector (#5285)

* Initial commit to enable Yolox models with OpenVINO in Frigate

* Fix ModelEnumtType import error in openvino.py

* Initial edit of the docs to include verbage about yolox

* Initial edit of the docs to include verbage about yolox

* Elaborate configuration and limitations in docs.

* Add capability to dynamically determine number of classes in yolox model

* Further refinements

* Removed unnecesarry comments, improved documentation, addressed PR items

* Fixed lint formatting issues

frigate/detectors/detector_config.py

@@ -23,6 +23,11 @@ class InputTensorEnum(str, Enum):
     nhwc = "nhwc"
 
 
+class ModelTypeEnum(str, Enum):
+    ssd = "ssd"
+    yolox = "yolox"
+
+
 class ModelConfig(BaseModel):
     path: Optional[str] = Field(title="Custom Object detection model path.")
     labelmap_path: Optional[str] = Field(title="Label map for custom object detector.")
@@ -37,6 +42,9 @@ class ModelConfig(BaseModel):
     input_pixel_format: PixelFormatEnum = Field(
         default=PixelFormatEnum.rgb, title="Model Input Pixel Color Format"
     )
+    model_type: ModelTypeEnum = Field(
+        default=ModelTypeEnum.ssd, title="Object Detection Model Type"
+    )
     _merged_labelmap: Optional[Dict[int, str]] = PrivateAttr()
     _colormap: Dict[int, Tuple[int, int, int]] = PrivateAttr()