Tidy names and locations of modules

- Rename old "model_management" directory to "model_management_OLD" in order to catch
  dangling references to original model manager.
- Caught and fixed most dangling references (still checking)
- Rename lora, textual_inversion and model_patcher modules
- Introduce a RawModel base class to simplfy the Union returned by the
  model loaders.
- Tidy up the model manager 2-related tests. Add useful fixtures, and
  a finalizer to the queue and installer fixtures that will stop the
  services and release threads.

invokeai/backend/onnx/onnx_runtime.py

@@ -8,6 +8,7 @@ import numpy as np
 import onnx
 from onnx import numpy_helper
 from onnxruntime import InferenceSession, SessionOptions, get_available_providers
+from ..raw_model import RawModel
 
 ONNX_WEIGHTS_NAME = "model.onnx"