final tidying before marking PR as ready for review

- Replace AnyModelLoader with ModelLoaderRegistry
- Fix type check errors in multiple files
- Remove apparently unneeded `get_model_config_enum()` method from model manager
- Remove last vestiges of old model manager
- Updated tests and documentation

resolve conflict with seamless.py

invokeai/backend/lora.py

@@ -10,6 +10,7 @@ from safetensors.torch import load_file
 from typing_extensions import Self
 
 from invokeai.backend.model_manager import BaseModelType
+
 from .raw_model import RawModel
 
 
@@ -366,6 +367,7 @@ class IA3Layer(LoRALayerBase):
 
 AnyLoRALayer = Union[LoRALayer, LoHALayer, LoKRLayer, FullLayer, IA3Layer]
 
+
 class LoRAModelRaw(RawModel):  # (torch.nn.Module):
     _name: str
     layers: Dict[str, AnyLoRALayer]