BREAKING CHANGES: invocations now require model key, not base/type/name

- Implement new model loader and modify invocations and embeddings

- Finish implementation loaders for all models currently supported by
  InvokeAI.

- Move lora, textual_inversion, and model patching support into
  backend/embeddings.

- Restore support for model cache statistics collection (a little ugly,
  needs work).

- Fixed up invocations that load and patch models.

- Move seamless and silencewarnings utils into better location

invokeai/backend/util/silence_warnings.py

@@ -0,0 +1,28 @@
+"""Context class to silence transformers and diffusers warnings."""
+import warnings
+from typing import Any
+
+from diffusers import logging as diffusers_logging
+from transformers import logging as transformers_logging
+
+
+class SilenceWarnings(object):
+    """Use in context to temporarily turn off warnings from transformers & diffusers modules.
+
+    with SilenceWarnings():
+        # do something
+    """
+
+    def __init__(self) -> None:
+        self.transformers_verbosity = transformers_logging.get_verbosity()
+        self.diffusers_verbosity = diffusers_logging.get_verbosity()
+
+    def __enter__(self) -> None:
+        transformers_logging.set_verbosity_error()
+        diffusers_logging.set_verbosity_error()
+        warnings.simplefilter("ignore")
+
+    def __exit__(self, *args: Any) -> None:
+        transformers_logging.set_verbosity(self.transformers_verbosity)
+        diffusers_logging.set_verbosity(self.diffusers_verbosity)
+        warnings.simplefilter("default")