Migration to CircleCI from Github actions

[rpanman-sonatype]

This PR moves the pipeline from GitHub Actions to Circle CI.

[bhamail]

Nice to see a CircleCI build happening. Some inline comments. Please holler if I can help.

[bhamail]

FWIW, one of my favorite features of CircleCI is the ability to run a CI build locally. It appears using when to determine which branch to build causes issues when trying to run a local build. Changing this to use filters: branches: only plays nice with local builds. Here's a snippet if you're interested:

workflows:
  develop-branch-workflow:
#    when:
#      equal: ['develop', << pipeline.git.branch >>]
    jobs:
      - enforce-commit-standards:
          filters:
            branches:
              only:
                - develop

With the above change, you could run a local build (after installing the CircleCI CLI tool - see: https://github.com/sonatype-nexus-community/nancy/blob/4a884909184b2888df89c2f596657b4cc88fb3de/.circleci/circleci-readme.md, and feel free to copy relevant parts of that .circleci/circleci-readme.md into this project if you like), you could run a local build using these commands:

circleci config process .circleci/config.yml > .circleci/local-config.yml
circleci local execute -c .circleci/local-config.yml --job 'enforce-commit-standards'

Given the above, you might also consider adding the .circleci/local-config.yml to the project .gitignore file:

# ci config for local ci build
.circleci/local-config.yml

BTW, the timing of this change happens to land when there is s known issue with local CircleCI builds and Docker vgroup2, so please ping me if you try a local build and the build does not launch.

[rpanman-sonatype]

Great, thanks Dan, I'll take a look - that looks like it would make writing new steps faster. In general I'm finding CircleCI much more pleasant to use than GitHub Actions or Jenkins. That might be because my first foray into CI/CD used Gitlab CI/CD and the YAML structure is similar, or it might just be the pretty GUI and good documentation :-)