[FIX] web: sort relational fields by their names

When sorting records according to a many2one field in a list view
embedded in a form view, the js would sort according to their ids,
in a seemingly arbitrary order.
Thus sorting records according to a field with values in ("a", "b", "c")
could be sorted as "a", "a", "c", "b" instead of "a", "a", "b", "c".
We make the comparison on the name of the field instead.

opw 1838860