Migrate Play telemetry samples to this repo

[ignasi35]

Move https://github.com/playframework/play-samples/blob/2.8.x/play-scala-telemetry-example and
https://github.com/playframework/play-samples/blob/2.8.x/play-java-telemetry-example to this repository.

[ignasi35]

Consider moving the 2.7.x version of those samples too(?)

[marcospereira]

Consider moving the 2.7.x version of those samples too(?)

I don't think so. Let's keep this focused on the latest versions only (so we won't need to maintain samples for Lagom 1.5, Akka 2.5, etc).