Add api support for user selectable columns
One of the desirable UI RFEs is to have support for "user selectable" columns. For example on pages like host list or organizations list a particular user might want to only see the list of organization labels and not care about the rest of the columns. The user would want this information stored and the future visits to that same page should get rendered based on what the user chose.
To this effect we need to facilitate a data model + api controllers so that plugins like Katello can make use of this .
Fixes #22624 - User selectable columns model + api
Adding initial bindings to user selectable columns. This model + api is
going to be used in work related Katello plugin's subscription pages.
The main intesnt of this PR is to provide a basic model where a user can
store "desirable or interested columns for a resource"
When the user for example says "I want to only see name column in
subscriptions" , we need model that would store that information
(similar to widgets or preferences.)
This commit facilitates that.