feat(telemetry): add metrics to count the number of builds

[sylvain-reynaud]

Closes #16

Ready to be reviewed !

[thomasgouveia]

Hi @sylvain-reynaud, thanks for the PR ! The idea is here, but you're wrong on the component.

registry and controller are two separated components. I've added in #13 the ability to the controller only to expose metrics. To work properly, you need to add a metrics server to the registry also. You can refer to this commit to learn how to do this.

Also, I prefer to have a dedicated package telemetry for each components. As we don't really know if the registry will be shipped with future release of Morty right now, It will be more easier to clean up files if we remove it.

To wrap up, what you need to change in your PR :

• Add a metrics server to the registry
• Add a telemetry package into the registry folder (and the code in it for sure)
• Update the configuration of the registry so we can pass a custom port for the metrics server

Feel free to ask questions if you need more details!