Rudder

Currently, ncf-builder lives on the same web server as the Rudder web interface, but when it is loaded from Rudder, the user arrives on a seemingly completely separate interface. This is confusing, and introduces bugs like #5676 (authentication issues).

Let's add a new page in the Rudder web interface, called "Technique editor", and include just a title (like the one on the Groups page, "Groups hierarchy", for example) and an iframe containing ncf-builder (with the standard white box in the background).

This approach will make it so that all requests to ncf-builder actually go via Rudder's interface, so authentication will be dealt with automatically, and the user will remain "inside" Rudder's web interface, so won't be lost.