examples in Kotlin

I have been using Apache Beam for few of my projects in production since the past 6 months and apart from Java, [Kotlin](https://kotlinlang.org/) also seems to work as well with no issues whatsoever.

But currently, the Github Repository of Apache Beam contains examples only in Java which might be an issue for other developers who want to use Apache Beam SDK with kotlin as there are no sample resources available.

That said, I would love to go ahead and add kotlin examples alongside the current java examples in the [Beam repository](https://github.com/apache/beam/tree/master/examples/java).

Imported from Jira [BEAM-6493](https://issues.apache.org/jira/browse/BEAM-6493). Original Jira may contain additional context.
Reported by: the-dagger.