Pluggable analytics

[nbrooke]

It's useful to keep a basic analytics endpoint in SteamcLog so that we have one place to go to to make analytics calls, but unlike logging and crash reporting we can't really pick a fixed default (though we may pick a soft default, that can be overridden, eventually). We want some way to be able to plug in particular analytics tools depending on the project.

Basic design is to add an AnalyticsDestination protocol that basically provides the same endpoint as the main analytics call, have the ability to register AnalyticsDestination with the system, and basically just make the analytics call a pass through to the AnalyticsDestination object(s) that have been registered.

If it isn't merged by the time this is worked on, it probably makes sense to just do this on the sentry branch, since that branch has already disabled the old fixed default of Fabric Answers.