Add more compose files to the scenarios-to-go collection

[glenacota]

The folder scenarios-to-go contains a collection of docker-compose files to spin up simple Elastic clusters, useful to practice with Elasticsearch.

Let's add more docker-compose files!

• [x] update the compose files in v7.4 to the latest version of the stack (v7.9, as of Sep 28)
• [x] an Elasticsearch cluster synced with a MySQL db via Logstash
• [ ] a sample application that is sending metrics/logs to a cluster via Beats
• [ ] a sample application that is sending metrics/logs to a cluster using the Elastic Agent
• [ ] a sample application that is sending traces to a cluster using the Elastic APM tools
• [ ] a cluster with the security features enabled
• [ ] ...