Produce logs for the analytics module

[MaelREBOUX]

In order to produce usage statistics for a geOrchestra instance, the gateway must produce logs understandable by the Analytics module, currently under development.

The expected log format is described here: https://github.com/georchestra/analytics/blob/main/README.md#analytics-log-format

To begin with, it is proposed to simply output this information in a log file. Knowing that this can be a sensitive point on heavily used instances. We must therefore anticipate another method of communicating data to Analytics.

A question is also : who manage the rotation of the logs file ?