Add code examples using Apache Flink with Flink Scala API

[geazi-anc]

In order to improve the understanding of this library and Apache Flink for those who have never tried it before, I think a directory in the repo with code examples is a good way to start.

Examples both using SBT and Scala CLI, where the last is a great tool to build Flink scripts. In this repository, by @novakov-alexey, there are many useful codes to move to here.