Feature transfer refs

Created by: dimitriredp

Features work defined by the following story https://oecd.plan.io/issues/20252

This works is a continuation of a previous one, for the "export" of a structure, in a sense that it rely on the same 'with or without refs' get of a sdmx-xml structure.

On the same logic a new component view refs-selector has been created, allowing to have the same sub menu view used for both export structure and transfer artefact actions.

During tests it has been noted that for a transfer with all references, a 207 code could be return by the api in case of some artefacts rejected (but not all of them), like in case of them already defined in target space. So 207 is now managed with a warning (instaed of error).