Introduce FlussSink for Flink DataStream API

[polyzos]

#908

[MehulBatra]

With some guidance, I would love to take a Jab at it @wuchong @polyzos

[polyzos]

@MehulBatra im already working on this

[MehulBatra]

Oh okay, if you need any help for later parts feel free to count me in!

[polyzos]

@MehulBatra definitely will do 🙏

[wuchong]

implemeted by #627