FiberLocal / IOLocal logger wrapper

[kubukoz]

hopefully self-explanatory: it would be great to have a wrapper for loggers that would allow one to pass structured logging context in a more implicit fashion.

This would probably involve creating a root logging context (the default value of the IOLocal), then using that in a wrapped logger so it passes the context to the underlying logger (e.g. slf4j).

[wunderk1nd-e]

Would something like this be helpful?
#676

[kubukoz]

Yes, that's pretty much what I was looking for :)

Maybe some utility that would create the IOLocal for you would also be nice.

[morgen-peschke]

I want to flag that we currently have 3 4 PRs working on this functionality (or functionality very similar to it), and we should probably reconcile them so we get the best result:

• Add some helpers for using Kleisli or IOLocal for logging context #676
• Adds a StructuredLogger based on cats.mtl.Ask #900
• Update #676: Adopt cats.mtl.Local for Logging Context and IOLocal #905
• Add logger with Local semantics #909

[kubukoz]

#676 can be closed, #905 is a direct continuation. #900, on the other hand...