Expose Webform settings in content type form

Thanks @barraponto. This is a well-written patch. The code looks good and comprehensive, but I'm mostly wondering if this is something that *should* be done. I know this will make Webform match some common conventions: e.g. Comments, Menu items, Translation etc. all place items on the content type pages. However I don't think enabling Webform on more than one content type is actually very common use-case (is it?) Most users I know just use the Webform content type that Webform comes with out of the box. Sometimes having more content types that are Webform-enabled just confuses the editorial teams.

So in short, I'm questioning if we should do this because I think it'd be increasing the visibility of a less-important option. Users hardly ever need to visit the Webform settings page, but they probably modify their content types regularly. I don't want to push up an option that people don't regularly need or use.

On the other hand... this would provide a place for us to expose the "webform_primary_node_types" variable, which right now is ONLY in code. A "primary" node type (such as the "webform" content type) has some slightly different behaviors, such as when you click "Save" on new nodes it takes you to the Webform components page instead of the front-end view version of the node.

I see where you're coming from on this request; I've just got my reservations about it.

@barraponto: may you also give a hand on review #2062235: Split webform_node_types as content type specific.? I try to merge part of your patch into my issue.

Most likely this issue is now duplicated and already merged into main stream ;-)