1. add a /sync route for synchronizing the in-memory model lists to
models.yaml, the models directory, and the autoimport directories.
2. add optional destination_directories to convert_model and merge_model
operations.
3. add /ckpt_confs route for retrieving known legacy checkpoint configuration
files.
4. add /search route for finding all models in a directory located in the server
filesystem
The list models route should just be the base route path, and should use query parameters as opposed to path parameters (which cannot be optional)
Removed defaults for update model route - for the purposes of the API, we should always be explicit with this
The `ModelsList` OpenAPI schema is generated as being keyed by plain strings. This means that API consumers do not know the shape of the dict. It _should_ be keyed by the `SDModelType` enum.
Unfortunately, `fastapi` does not actually handle this correctly yet; it still generates the schema with plain string keys.
Adding this anyways though in hopes that it will be resolved upstream and we can get the correct schema. Until then, I'll implement the (simple but annoying) logic on the frontend.
https://github.com/pydantic/pydantic/issues/4393
