web app: use SWHIDs everywhere in metadata view

Reworking the "show metadata" pop-up in the Web UI is a long-running theme and probably won't be completed soon.

But there is an important low-hanging fruit that we can easily fix: when opening the widget, e.g., from https://archive.softwareheritage.org/browse/origin/directory/?origin_url=https://github.com/torvalds/linux , the directory, object_id, revision, etc. fields are all showing raw sha1 checksums. We should instead use SWHIDs everywhere. It would also be nice to move all SWHIDs to the top of the fields list, because they denote the outgoing edges from the Merkle DAG node that is currently being visited.

---

Migrated from T2848 (view on Phabricator)