https://meta.wikimedia.org/wiki/Special:SpecialPages#mw-specialpagesgroup-campaignevents
CampaignEvents lists 7 special pages on Special:SpecialPages, but only 2 work by default.
The other five lead to error page, like below, because they require parameter which is impossible to provide from Special:SpecialPages. There's also no way to provide that when we reach the error page, save by manually modifying the URL
They should either be unlisted (I believe they're already accessible via more approproate entry points) or they should provide default input form instead of the error they show.
Acceptance Criteria:
- Keep the special pages as listed
- If there is no valid id, include the following text: "This page has no valid event ID. Enter a valid event ID or view all events in the Collaboration list."
- Link "Collaboration list" to Special:AllEvents in the wiki that the user is on

