Simplify `List.filterMap (\foo -> if x then Just foo else Nothing)` to `List.filter (\foo -> x)`

[miniBill]

Example of things the rule would report:

List.filterMap (\foo -> if x then Just foo else Nothing)
--> List.filter (\foo -> x)

Example of things the rule would not report:

List.filterMap (\foo -> if x then Just (foo + 2) else Nothing)

I am looking for:

• Someone to implement it with/for me

[miniBill]

As usual, this is not code one writes, but the result of a previous simplification

[lue-bird]

I often write the filterMap because it's easier to understand and maintain for me but I'm not opposed to this simplification (less code and faster).