chore: import upstream snapshot with attribution

invokeai/backend/raw_model.py

@@ -0,0 +1,22 @@
+from abc import ABC, abstractmethod
+from typing import Optional
+
+import torch
+
+
+class RawModel(ABC):
+    """Base class for 'Raw' models.
+
+    The RawModel class is the base class of LoRAModelRaw, TextualInversionModelRaw, etc.
+    and is used for type checking of calls to the model patcher. Its main purpose
+    is to avoid a circular import issues when lora.py tries to import BaseModelType
+    from invokeai.backend.model_manager.config, and the latter tries to import LoRAModelRaw
+    from lora.py.
+
+    The term 'raw' was introduced to describe a wrapper around a torch.nn.Module
+    that adds additional methods and attributes.
+    """
+
+    @abstractmethod
+    def to(self, device: Optional[torch.device] = None, dtype: Optional[torch.dtype] = None) -> None:
+        pass