Breaking this discussion out of D7357.

IMO, swh-web depends on client-side Javascript more than it needs to:

1. The origin search does not work at all
2. The "Save Code Now" form is a noop without it
3. The "Add Forge Now" form works but shows an obscure error (T4053)
4. Tabs in "Save Code Now" and "Add Forge Now" don't work
5. We had to repeatedly fix history issues with these tabs, even with JS enabled (T4050, rDWAPPS39bab96e9f0484e04fe837b5162d889b8040980a, an old diff I was working on that needed to add a tab somewhere, ...)

All these could be replaced by normal HTML pages and forms; this would allow them to work everywhere, and be less brittle.

(Note that I'm not advocating for complete removal of client-side Javascript; it is fine to use it for Datatables, lazy loading of origin statuses, lazy loading of status.softwareheritage.org, lazy loading of counters, querying GitHub's API, ...)