feat: introduce --read-paths to threat PATH as a file containing manifest paths

[Tyrael]

Summary

Introducing --read-paths as a new boolean config option, defaulting to false.
When set to true, we would consider PATH as a file containing puppet manifests to lint, separated by newlines.
This is my first contribution here, so I dont't expect this to be accepted as-is, just let me know what should I improve/change to get this right.

Additional Context

We are using puppet-lint as part of our cicd pipelines, and we currently have to resort to xargsing each modified puppet manifest in and executing puppet-lint for each file.
With this change we would be able to specify a list of files to lint in a single puppet-lint execution

Checklist

• 🟢 Spec tests.
• 🟢 Acceptance tests.
• Manually verified.

[CLAassistant]

All committers have signed the CLA.

[bastelfreak]

Hi, stupid question:

we currently have to resort to xargsing each modified puppet manifest in and executing puppet-lint for each file.

Why? puppet-lint accepts directories, globbing and multiple file paths already.

Besides that my recommendation is to always lint all files. Otherwise you won't find issues that are marked by new linting rules, e.g. #175

[Tyrael]

Why? puppet-lint accepts directories, globbing and multiple file paths already.

we have a monorepo with a huge amount of modules and files, linting all of the repo for each MR would be a huge waste of resources and would slow down the lint pipeline a ton.

I've seen the support for passing a directory and globbing, but I couldn't find a way to pass an arbitrary list of files to puppet-lint, let me know if I missed something.

Besides that my recommendation is to always lint all files. Otherwise you won't find issues that are marked by new linting rules, e.g. #175

ofc. when changing puppet-lint version or .puppet-lint.rc we should and do rerun the linter on all files.

[Tyrael]

@bastelfreak could you please approve the workflow execution?

[bastelfreak]

but I couldn't find a way to pass an arbitrary list of files to puppet-lint

you can pass them on the cli like puppet-lint --fix manifests/foo.pp manifests/bar.pp