storage*: origin_get(Iterable[str]) -> Iterable[Optional[Origin]]
This:
- drops the legacy behavior (no more input as list of dicts or even one dict).
- aligns with other _get endpoints (only 1 iterable of identifiers as input,
here the origin urls).
- migrates towards returning an iterable of optional origin model
objects (again the optional part is alignment with existing get endpoint)
Related to T645