R1:ebb7807bb41e

Fix an issue with URIs missing trailing slashes, like "/maniphest"

Summary:
In D3144, I made us look in application maps to find routing rules. However, we don't process //all// the maps when we 404 and try to do a "/" redirect. Process all of the maps.

Additionally, in D3146 I made the menu items application-driven. However, some pages (like 404) don't have a controller. Drop the requirement that the controller be nonnull.

Test Plan:
- Visited "/maniphest", got a redirect after this patch.