feat: port Data.List.BigOperators.Basic (#1380)

- Initial file copy from mathport
- Mathbin -> Mathlib; add import to Mathlib.lean


Co-authored-by: ChrisHughes24 <chrishughes24@gmail.com>
Co-authored-by: Scott Morrison <scott.morrison@gmail.com>

Mathlib.lean

@@ -243,6 +243,7 @@ import Mathlib.Data.Int.Units
 import Mathlib.Data.KVMap
 import Mathlib.Data.LazyList
 import Mathlib.Data.List.Basic
+import Mathlib.Data.List.BigOperators.Basic
 import Mathlib.Data.List.Card
 import Mathlib.Data.List.Chain
 import Mathlib.Data.List.Defs