feat: port Data.Set.Intervals.Instances (#1068)

Co-authored-by: Moritz Firsching <firsching@google.com>
Co-authored-by: qawbecrdtey <qawbecrdtey@kaist.ac.kr>
Co-authored-by: Lukas Miaskiwskyi <lukas.mias@gmail.com>
Co-authored-by: Ruben Van de Velde <65514131+Ruben-VandeVelde@users.noreply.github.com>
Co-authored-by: Johan Commelin <johan@commelin.net>

Author: 6 people

Mathlib.lean

@@ -474,6 +474,7 @@ import Mathlib.Data.Set.Intervals.Basic
 import Mathlib.Data.Set.Intervals.Disjoint
 import Mathlib.Data.Set.Intervals.Group
 import Mathlib.Data.Set.Intervals.Infinite
+import Mathlib.Data.Set.Intervals.Instances
 import Mathlib.Data.Set.Intervals.IsoIoo
 import Mathlib.Data.Set.Intervals.Monoid
 import Mathlib.Data.Set.Intervals.Monotone