Internal Add-ons API doesn't have a details page so "I'm Feeling Lucky" is broken

[tofumatt]

Since the move to config-based API prefixes, we hit /api/v3/internal/addons/addon/${slug} when we find an exact match for an add-on. But this API doesn't (yet) exist in add-ons server, so nothing happens.

Filing here for posterity, but ultimately @diox said an internal details endpoint was on the table and this should eventually be fixed upstream in the API.

[tofumatt]

To be clear: this only happens in the admin app because /internal is prefixed to all its URLs. Everything is still fine elsewhere.

[diox]

Fixed in #3648