loader-core: RawExtrinsicMetadata: update to use the API in swh-model 1.0.0
Test Plan
Tests will fail because swh-model 1.0.0 is not released yet.
EDIT: after the swh-model release, this build still fails because swh-storage needs a release too (swh-storage!650 (closed))
Migrated from D5177 (view on Phabricator)