build: migrate golangci-lint to v2

[diatrcz]

Migrate golangci-lint to v2 from v1.

[CLAassistant]

All committers have signed the CLA.

[pyrooka]

I left a few comments to consider. Haven't tested all of them so expect lint failures, but we should keep things default and as strict as possible. Let me know if you have any questions!

These comments/suggestions also apply to IBM/platform-services-go-sdk#411

[pyrooka]

I looked into the changelog of golangci-lint and found this:

⚠️ Merge staticcheck, stylecheck, gosimple into one linter (staticcheck) (cf. Migration guide)

So after thinking about this a little I have to realize that completely disabling staticcheck is not a good idea as we also disable the other 2 - sorry for suggesting this previously! :)

Sooo, I'd recommend to disable only the rules that cause issues. I've found 2 ways to do that:

1. Setting the check in the staticcheck config (see here )
2. Ignoring specific messages from the staticcheck linter. Here is an example how to do it (at the bottom of the config in the linked section).

Sorry for the confusion!

[diatrcz]

I prefer the approach of enabling and disabling rules inside the check in the linter's config. Only downside is that this way you have to list every single rule that you want to use with the linter. Although somehow this way it includes more rules with the linter as well. Nevermind I can't read 😅