Background: Some hook names changed when moving from the old to the new hook system. This is because php does not support colon characters in interface names, therefore the colons were replaced with underscores. This can cause a confusing situation, where as an extension developer I wouldn't know what name to use to register the hook.

The canonical name of the hook should be documented in the hook interface, so it becomes discoverable.

Originally, this task asked for the canonical name of the hook to be a constant (NAME) in the hook interface. However, that causes a conflict when a class implements more than one hook interface. Implementing multiple hook interfaces in a single class is explicitly supported and desirable, so a NAME constant can't work.