Replace Google Analytics

[retrodaredevil]

We should replace the usage of Google Analytics with something more open, and also something that isn't designed to be used for web sites. We also have this to worry about:

Universal Analytics will no longer process new data in standard properties beginning July 1, 2023. Prepare now by setting up and switching over to a Google Analytics 4 property.

I'm open to suggestions on what to use because I don't see that many great free alternatives. User privacy is important, but it would also be nice to be able to track the number of users using SolarThing at a given time, which does require a unique ID of some sort.

Right now each SolarThing program has its own unique ID. It would be nice to do a code change to somehow centralize that unique ID in a shared SolarThing data directory. (I'm also in favor of restructuring the program directory, so maybe this could be done when or if that happens).

Please provide any suggestions below. Remember you can disable analytics here by going here: https://solarthing.readthedocs.io/en/latest/config/analytics.html