Feature/custom sorting via options

I'm sure this code could be cleaned up, and there are likely edge cases, but I wanted to get this out here to start a discussion as to whether or not people would find this useful? Here are my two use cases:

1. I want to present one of the attributes differently so I create a new method on the model called, for example, display_phone, where I do some formatting of the sanitized stored phone number data. The problem is that once I do that, I can't sort by that field because the db only knows about phone not display_phone. With this change I can specify an order: 'phone' option to the display_phone field on the dashboard and allow that pretty displayed data to be sorted by its underlying db column.

    phone: Field::String,
    display_phone: Field::String.with_options(
      searchable: false,
      order: 'phone',
    ),

2. I am displaying a list of Clinics that belong to an Organization and I would like to be able to sort the clinic list by this associated model's name field. By allowing order: 'organization.name' to be specified, we can detect that we're sorting across a join table with the presence of a . and join to that table and order by the specified attribute. One trick/bummer here is that with this implementation, we need to leave the plurality of the join table name to be specified by the user. So in this case with a Clinic#index view where a Clinic belongs to an Organization it'd be a singular organization.name specified.

    organization: Field::BelongsTo.with_options(
      order: 'organization.name',
    ),