Multiple refinements on loaders:

- Cache stat collection enabled.
- Implemented ONNX loading.
- Add ability to specify the repo version variant in installer CLI.
- If caller asks for a repo version that doesn't exist, will fall back
  to empty version rather than raising an error.

invokeai/frontend/install/model_install2.py

@@ -505,7 +505,7 @@ def list_models(installer: ModelInstallService, model_type: ModelType):
     print(f"Installed models of type `{model_type}`:")
     for model in models:
         path = (config.models_path / model.path).resolve()
-        print(f"{model.name:40}{model.base.value:14}{path}")
+        print(f"{model.name:40}{model.base.value:5}{model.type.value:8}{model.format.value:12}{path}")
 
 
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