Replaces filter or filterNot on a Set with intersect or diff if possible.

Before:

set.filter(others.contains(_))
set.filterNot(others.contains))
set.filter(x => !others.contains(x))
set.filterNot(x => !others.contains(x))

After:
set.intersect(others)
set.diff(others)
set.diff(others)
set.intersect(others)