Add log logger to ergot crate

[tommasoclini]

This allows treating ergot's logs differently to log normal logs through ergot

[jamesmunns]

@tommasoclini could you take a look at #120 as an alternative impl? I think this could be done without adding any additional unsafe as this PR does.

[tommasoclini]

@tommasoclini could you take a look at #120 as an alternative impl? I think this could be done without adding any additional unsafe as this PR does.

Doesn't that use the global logger? What happens if an interface has a worker task and it logs stuff after sending data?

[jamesmunns]

Yes, it does act as the global logger, as of now, we do need to somehow (?) make sure that we don't enable the level below the level that the system otherwise logs, e.g. using debug or trace level.

I'm not sure if I understand how this PR would avoid that, though!

[jamesmunns]

I spoke with @tommasoclini in chat, and I have a much better idea of what he had in mind now! I have some free time, so I'm going to merge this now and iterate on it in a follow up PR.

Thank you Tommaso for taking to he time to help me understand!