Explore adding Fragment objects

[jho406]

Closely related to #56 . This issue is about exploring the idea of adding a Props::Fragment object. Fragments are defined like this:

json.note(
  partial: [
    "club_notes/note",
    fragment: "club_note_#{@club_note.id}",
  ]
) do
# Empty block here
end

But it can be a bit tedious to define across different props templates if they are used elsewhere. I'm considering adding a Props::Fragment object that folks can inherit from. So we can turn the above to

class NoteFragment < Props::Fragment
end

json.note(NoteFragment.new(@club_note.id))

Internally we'll call something like responds_to?(:to_prop_options)which we can call to return the work done at #56