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/model_manager/load/memory_snapshot.py

@@ -5,7 +5,7 @@ import psutil
 import torch
 from typing_extensions import Self
 
-from invokeai.backend.model_management.libc_util import LibcUtil, Struct_mallinfo2
+from ..util.libc_util import LibcUtil, Struct_mallinfo2
 
 GB = 2**30  # 1 GB
 
@@ -97,4 +97,4 @@ def get_pretty_snapshot_diff(snapshot_1: Optional[MemorySnapshot], snapshot_2: O
     if snapshot_1.vram is not None and snapshot_2.vram is not None:
         msg += get_msg_line("VRAM", snapshot_1.vram, snapshot_2.vram)
 
-    return "\n" + msg if len(msg) > 0 else msg
+    return msg

invokeai/backend/model_manager/load/model_loaders/lora.py

@@ -7,7 +7,7 @@ from pathlib import Path
 from typing import Optional, Tuple
 
 from invokeai.app.services.config import InvokeAIAppConfig
-from invokeai.backend.embeddings.lora import LoRAModelRaw
+from invokeai.backend.lora import LoRAModelRaw
 from invokeai.backend.model_manager import (
     AnyModel,
     AnyModelConfig,

invokeai/backend/model_manager/load/model_loaders/textual_inversion.py

@@ -5,7 +5,7 @@
 from pathlib import Path
 from typing import Optional, Tuple
 
-from invokeai.backend.embeddings.textual_inversion import TextualInversionModelRaw
+from invokeai.backend.textual_inversion import TextualInversionModelRaw
 from invokeai.backend.model_manager import (
     AnyModel,
     AnyModelConfig,