[FEATURE] - Add golangci-lint GitHub Action

[alex1989hu]

Is your feature request related to a problem? Please describe

Using popular lint tool golangci-lint would help to keep the code cleaner and fix the already existing issues.

Describe the solution you'd like

• Add .github/workflows/golangci-lint.yml
• Remove lint, fmt, check-fmt and vet job from .github/workflows/go_test.yml
• Remove fmt, check-fmt and vet from Makefile
  • Optionally keep lint but to call golangci-lint
• Create a minimal ~ permissive .golangci.yml as starting point
  • Listing currently enabled linters https://golangci-lint.run/usage/linters/#enabled-by-default-linters
• Fix errors reported by the default configuration
• Enable more linters and fix issues reported by the newly activated linters

Example YAML based on the official repo and on your current workflow https://github.com/golangci/golangci-lint-action#how-to-use

name: golangci-lint
on:
  push:
    branches:
      - master
  pull_request:
    branches:
      - master
jobs:
  golangci:
    strategy:
      matrix:
        go-version:
          - 1.14
          - 1.15
    name: lint
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: golangci-lint
        uses: golangci/golangci-lint-action@v2
        with:
          version: v1.33

Describe alternatives you've considered

The code already provides an alternative: golang.org/x/lint/golint

Additional context

N/A

[JohnRoesler]

Hey @alex1989hu - thanks for the suggestion. This looks pretty cool. Running it locally I can see some things we should address, and some we already knew about but just haven't gotten around to solving yet.