Add "Update external links" to the release actions page

[RustyNova016]

It would be nice to also be able to go directly to the release actions page to update the links, as it's most people just go to it directly when they see that the release is already in MB

[kellnerd]

This won't work, the release actions page only uses the external links which are already attached to the MB release, so it won't find any new links.
Doing additional lookups is out of scope for the release actions page as you can't see potential mismatches. You should really be doing a new lookup instead, once #73 is fully implemented there will be even more release properties than external links which can be updated on MB.