Add nargs as a supported linter

[palash25]

Thank you for creating the issue!

Please include the following information:

1. Version of golangci-lint: golangci-lint --version (or git commit if you don't use binary distribution)
2. Config file: cat .golangci.yml
3. Go environment: go version && go env
4. Verbose output of running: golangci-lint run -v

https://github.com/alexkohler/nargs

[jirfag]

hi,
why isn't unparam sufficient for you? it looks like a much less efficient version of unparam

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[FdeFabricio]

There are some cases that unused parameters are ignored by unparam, called as "dummy implementation", which are not ignored by nargs. mvdan/unparam#49

In terms of efficiency, I don't know much...