Quality of life updates for LoggerFactory

[morgen-peschke]

Adds methods to return updated versions that configure the loggers they produce using addContext and withModifiedString.

This should make it easier to migrate from passing around a single SelfAwareStructuredLogger and using a LoggerFactory.

[rossabaker]

I don't know what the LoggerFactoryGen supertype is for, but I'll ask: would this have worked on LoggerFactoryGen? I think probably not, because then it wouldn't be able to return a LoggerFactory?

Assuming that's a bad idea, 👍

[morgen-peschke]

I don't know what the LoggerFactoryGen supertype is for, but I'll ask: would this have worked on LoggerFactoryGen? I think probably not, because then it wouldn't be able to return a LoggerFactory?

Assuming that's a bad idea, 👍

I'm pretty sure that it couldn't go on LoggerFactoryGen because they get passed through to methods which aren't on Logger, so we need the constraint that LoggerFactory adds that LoggerFactoryGen#LoggerType is SelfAwareStructuredLogger[F] instead of any Logger[F] subtype.