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/app/invocations/compel.py

@@ -17,9 +17,9 @@ from invokeai.app.invocations.primitives import ConditioningOutput
 from invokeai.app.services.model_records import UnknownModelException
 from invokeai.app.services.shared.invocation_context import InvocationContext
 from invokeai.app.util.ti_utils import extract_ti_triggers_from_prompt
-from invokeai.backend.embeddings.lora import LoRAModelRaw
-from invokeai.backend.embeddings.model_patcher import ModelPatcher
-from invokeai.backend.embeddings.textual_inversion import TextualInversionModelRaw
+from invokeai.backend.lora import LoRAModelRaw
+from invokeai.backend.model_patcher import ModelPatcher
+from invokeai.backend.textual_inversion import TextualInversionModelRaw
 from invokeai.backend.model_manager import ModelType
 from invokeai.backend.stable_diffusion.diffusion.conditioning_data import (
     BasicConditioningInfo,