[D8][UX] Add hidden and read-only field widgets (for the node edit form).

I am trying to port a fairly simple website to Backdrop. In that site, I use Field Extra Widgets which is a tiny utility module that simply adds two options for the edit form of fields: "hidden" and "read-only". This is for cases where one needs for example to provide a default value for a field, but wants to either prevent users from changing it when creating/editing the content or hide it out of their way (so that the form is not cluttered).

I am confident that I can port this module to contrib so that I can use it in this specific Backdrop-converted site, but I believe that such a tiny feature would be of value to core (it will be another thing to brag about Backdrop 1.5.0 in the DrupalSouth talk I might give ).

So, do I port it in contrib and see if we can merge it in core at some point in the future? ...or do I (please) get some guidance to add these small but very useful features in core now(-ish)?