[Feature] `iter` support running from a map

conc is very wonderful to writing concurrent code, thanks for your project!

Currently, there is only iter.Map() run from a slice. But sometimes we need to concurrently run from a map.

Could you consider provide a function like:

func RunFromMap[K comparable, V any, R any](input map[K]V, f func(*T, *V) R) []R

(iter.Map running from slice has occuppied the best name. The naming maybe a little hard to decide)