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/textual_inversion.py

@@ -8,8 +8,10 @@ from compel.embeddings_provider import BaseTextualInversionManager
 from safetensors.torch import load_file
 from transformers import CLIPTokenizer
 from typing_extensions import Self
+
 from .raw_model import RawModel
 
+
 class TextualInversionModelRaw(RawModel):
     embedding: torch.Tensor  # [n, 768]|[n, 1280]
     embedding_2: Optional[torch.Tensor] = None  # [n, 768]|[n, 1280]   - for SDXL models