Add partitionMap operation

[julienrf]

Scala 2.13 has introduced this operation to Iterables: https://www.scala-lang.org/api/current/scala/collection/Iterable.html#partitionMap[A1,A2](f:A=%3EEither[A1,A2]):(CC[A1],CC[A2])

[yannbolliger]

I will try this one. 🚀