Register a report button that triggers the ReportIncident dialog, using the hook provided by the DiscussionTools overflow menu feature in T340138: Add ellipsis / action menu to topic headers and individual comments.

In this task, we'll want to implement the yet-to-be-created hook in DiscussionTools that allows extensions to add an item to the overflow menu next to topic headers and comments.

The implementation for anonymous and temp users is still TBD.

For logged-in users, we should add a button with the text "Report" and an icon (TBD), with a CSS class that we can wire our Vue application to. The item should also include in a data property some information about the topic header ID or comment ID that it is linked with; the Vue app will make use of this in the reporting interrface.