dev: cleanup config package

[ldez]

The purpose of this cleaning is to facilitate contribution and maintenance.

The PR provides a homogeneous design:

• each configuration section have a dedicated file
• no anonymous structure
• the linters in the main Config structure are sorted alphabetically and the linters settings structures are also sorted alphabetically.

I created one commit by change like that it's easier to review.

[bombsimon]

Nice, looks much better structured and sorted! 🎉

Not sure the last commit is really provides increased maintainability, to me it's a bit stuttering to prefix every file in a directory with the same name (config/config_*) but I guess that's just personal preference.

^{Yes, I saw that reader.go was left but tbh I don't really see why this one wouldn't be prefixed as well since it's reading/parsing config.}

[ldez]

@bombsimon I added the last commit because the file reader.go is not a part of the Config struct, it can be confusing.
I'm also not a fan of the prefix config_ in the package config, but I didn't find a better idea.

Edit: I had not seen your very small comment 😄

[bombsimon]

I have no strong feeling hence the approve! If you think this is better than keeping the names go ahead and merge or wait for an additional review. I'm just appreciating your effort in maintaining this project!

[ldez]

I think I will drop the last commit because we are, at least you and me, not to be a fan of the prefix.