Add performance monitoring / telemetry

[TristanCacqueray]

The goal is to measure the performance of the different parts of the game. Here are some available options:

• prometheus.io, haskell packages prometheus-client or prometheus. Prometheus works by polling a text http endpoint, it supports counter and gauge. it can be used to query the metric directly, or it can be configured as a grafana data source.
• opentelemetry.io, haskell packages opentelemetry or tracing. Telemetry supports "spans" and events. Logs can be processed offline, for example with https://profiler.firefox.com/ , or sent to a live service like https://zipkin.io/ or https://www.jaegertracing.io/ .
• ekg, a standalone solution in pure haskell.

I think ekg would be the most user friendly as it should work straight from the web interface. Though we might get better results using an extra service.

[TristanCacqueray]

Here is an example of adding telemetry to stack: https://github.com/commercialhaskell/stack/pull/5260