feat(set): preliminaries for Haar measure (#3189)
`comp_sup_eq_sup_comp` is renamed `comp_sup_eq_sup_comp_of_is_total` and there is a new version that doesn't assume that the order is linear.
`set.image_injective` is renamed `function.injective.image_injective` (in the same way as the existing `function.surjective.preimage_injective`). `set.image_injective` is now an `iff`.
