OpenTelemetry example

[marychatte]

First commit is just copy of project kotlin-conf-testing

Second commit adds dependencies for OpenTelemetry and a task to run JaegerUI in a docker container. JaegerUI is used to visualise OpenTelemetry data

Third commit provides an example of usage KtorServerTracing plugin. It creates an instance of OpenTelemetry using AutoConfiguredOpenTelemetrySdk. Also, it adds an example of usage KtorServerTracing plugin and creates an extra parameter user_id to observe in traces

Notes:

• To run the example, you need to run task runWithDocker
• Docker container is restarting every run. It can be disabled here if needed
• After running, OpenTelemetry traces can be viewed at http://localhost:16686/
  An example uses some extractions for the KtorServerTracing plugin. They will be added to the plugin in the next opentelemetry-java-instrumentation release. A full list of extractions can be found here