Enhancement of the Packer FMT + Packer Validate Hooks

[schniber]

Enhancement of the Packer FMT + Packer Validate Hooks

🗣 Description

This PR enhances the following:
1- Packer fmt hook now not only checks but actually reformats all packer*.json or *.pkr.hcl. It also checks for *.pkrvars.hcl and if found formats them too.
2- Packer validate hook now accepts as input the *.pkrvars.hcl file which indicates to Packer with which parameters the Packer config can be validated with.

💭 Motivation and context

These enhancements are linked to the issue #3 I have created last week.

🧪 Testing

I have run tests on some packer configuration I am working on.
Additional details can be found on the README.md file that comes with this PR.

✅ Checklist

• This PR has an informative and human-readable title.
• Changes are limited to a single goal - eschew scope creep!
• All future TODOs are captured in issues, which are referenced
  in code comments.
• All relevant type-of-change labels have been added.
• I have read the CONTRIBUTING document.
• These code changes follow cisagov code standards.
• All relevant repo and/or project documentation has been updated
  to reflect the changes in this PR.
• Tests have been added and/or modified to cover the changes in this PR.
• All new and existing tests pass.

[mcdonnnj]

@schniber We use a skeleton system touched on in our development guide. This allows us to keep our linter and testing configurations consistent across all of our repos using cisagov/action-lineage.

Although your PR includes some useful functionality, in the process you have steamrolled everything else in this project. As an additional note here, packer fmt is only designed to service HCL2 configuration files as documented in the command help.

We would be happy to review a PR that adds the desired functionality, but we cannot accept a PR that intentionally creates discontinuity in one of our repositories.

[schniber]

Hello @mcdonnnj
Thanks for your feedback.
I have aligned the PR to the contribution guidelines, sorry for that this is my first ever contribution :)
All checks seem to have passed now.

Regarding the pkrvars.hcl files, those are also considered as HCL2 files.
Unless I am mistaken, It looks like packers documentation is not up to date/or is unclear on this point.
Still, the packer fmt function works when you point it out to a .pkrvars.hcl file.
=> You can have a look to this merged PR for more details : hashicorp/packer#10377

Please feel free to revert back to me in case you need any additional details.

Looking forward to hearing from you.

Bests