I also had to make the "New" operator a submenu in the
`File Context Menu`, so that you can still select the template.
This partially solves T61599. Currently the confirm dialog
is not shown when an already existing file is opened.
Implementing that requires a bit more work and will be
done in a separate patch.
Reviewers: brecht
Differential Revision: https://developer.blender.org/D4732