Add removing declarations from a set.

[mar-jac]

This function is designed to remove all declarations associated with a specific set, effectively clearing any links between the set and its declarations without specifying individual declaration identifiers. RemoveDeclarationsFromSet operates at a broader level, targeting all declarations associated with a set.

setName: The name of the set from which all declarations are to be removed.

Use RemoveAllDeclarationsFromSet when you need to completely clear a set of all its associated declarations, which might be useful in scenarios like resetting the set's configuration or prior to deleting the set itself.

[jessepeterson]

Thanks! As we talked about, to play devil's advocate: why not just use the enumerate and remove operations already present? :)

If not then this will require some more things:

1. Implementing the file storage backend, too.
2. Making it a part of the general all storage.
3. Create a storage test for it.
4. Exposing it to the REST-ish API.
5. Creating script for that exposed API
6. Docs (OpenAPI & ops guide)

Alternatively you could implement something in the storage interface that retrieves the list of set declarations, and then removes them all. This could be backend-agnostic. But you'd still need steps 3-6. See #102 for an example of a storage change that changes all of the above.