Add supervisor strategy support for Flow#throttle

[He-Pin]

Motivation: After took a look at Akka.NET's release note and I found pekko-stream don't has this too. refs: https://github.com/akkadotnet/akka.net/pull/6886

Would be nice to have this support.

[nvollmar]

Goes into the same direction as #624?

[He-Pin]

I will try to work on https://github.com/apache/incubator-pekko/issues/624 this weekend.