feat: add logger interface

[aymanbagabas]

Pass a custom logger to log messages

[KyleFromKitware]

This is definitely an improvement. If you haven't already, I'd also suggest checking out logrus. It seems to be the de facto standard for logging in Go, and supports things like structured data. It's pluggable, you can use any logging backend you want with it. GitLab uses logrus, wrapped in their own wrapper.

[aymanbagabas]

This is definitely an improvement. If you haven't already, I'd also suggest checking out logrus. It seems to be the de facto standard for logging in Go, and supports things like structured data. It's pluggable, you can use any logging backend you want with it. GitLab uses logrus, wrapped in their own wrapper.

I would avoid using logrus since there are many different go loggers out there and each has its interface, plus it would bloat the package. Perhaps we could make this Logger interface structured instead

[KyleFromKitware]

Perhaps we could make this Logger interface structured instead

Yes, I think that would be a good idea too, and then on GitLab's side we could simply add a Logrus backend for your Logger interface.

[KyleFromKitware]

Cc: @ashmckenzie

[KyleFromKitware]

Looks good, one minor suggestion.

[codecov]

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