[#55137834] Add api doc for insights#destroy
[#56850952] Workfiles can again be created from the Workspace Quickstart menu.

We were accidentally passing the workfile create dialog a workspace, when it wanted
to be passed nothing so it could create a new workfile.

Also deleted a couple of random "dialog" classes from .hbs files, as they do
not seem to be used for anything (styling or eventing) anymore.