Add linter for Go

[maci3jka]

This PR improves the development experience. It adds to go checks the linter golangci-lint, aggregating the number of liners and adding annotations on the PR with found issues. Additionally, it introduces go.lint target to makefile which allows running the same set of linters locally.

[maci3jka]

example of working https://github.com/canonical/k8s-snap/pull/722/files

[HomayoonAlimohammadi]

Thanks a lot @maci3jka, Almost LGTM. Just minor comments and questions.

[bschimke95]

Going in the right direction.

Please enable all, see how much issues we get and post that here. Then we can create a PR that branches from this PR and fix all of those issues (if they are straightforward).

[HomayoonAlimohammadi]

Thanks a lot. This is wonderful. Now we have a shit ton of linting problems to fix. Merging this would cause the k8s-snap pipeline to get stuck in a failing state until everything is fixed which is not good. We can do 2 things:

1. Keep the PR open and gradually fix the issues
2. Change the base from main to a custom branch.

I would go with option 1 because when we're done with the feature branch, rebasing it on main will be a huge pain and is super error prone.
Options 1 is itself challenging tho. We will still need to make sure we constantly rebase on main to prevent a huge and problematic/conflicting rebase later on.
WDYT @bschimke95?

[bschimke95]

LGTM

[bschimke95]

I added a list of all linters and disabled them. Now I will gradually enable all of the linters and fix the relevant code pieces as separate PRs.