More List.minimum/maximum simplifications

List.minimum [ 1, 2, 3 ]
--> Just 1
List.minimum (1 :: [ 2, 3 ])
--> Just 1

List.maximum [ 1, 2, 3 ]
--> Just 3

List.minimum [ a, 1 ]
-- Not reported, but if there are duplicate values, then we can remove some of them
List.minimum [ 3, a, 1 ]
--> List.minimum [ a, 1 ]
List.minimum (3 :: list ++ [5])
--> List.minimum (3 :: list)
List.minimum ([3] ++ list ++ [5])
--> List.minimum ([3] ++ list)

List.minimum (List.repeat <positiveInt> x)
--> Just x
List.maximum (List.repeat <positiveInt> x)
--> Just x

If we know x <= y ✅

List.minimum (List.range x y)
--> Just x ✅
List.maximum (List.range x y)
--> Just y ✅