We were manually generating the IDs in order to pass them as data
attributes in the HTML in a component where we don't have access to the
form which has the inputs.
However, these data attributes only make sense when there's a form
present, so we can pass the form as a parameter and use it to get the
IDs.
We can now define a map as editable when there's an associated form,
which makes sense IMHO.
We were probably setting them separately to avoid having blank data
attributes in the HTML. However, when a data attribute is `nil`, Rails
doesn't write it in the HTML in the first place.
