replay: fix raw_extrinsic_metadata insertion and type annotation
due to missing type annotation of the storage argument of _insert_objects(), we missed a bug in the processing of raw_extrinsic_metadata objects, passing set() as arguments of storage add methods.
Also fix annotation of collision_aware_content_add(), the callable is expected to return a dict (and now we have an annotated storage, mypy is not happy any more).
Migrated from D6370 (view on Phabricator)