feat(scorecard): Implement batch provider for file checks

[djanickova]

Implement batch provider for file checks

This PR introduces a batch provider for file checks in scorecard. I took most of the logic from Patrick's POC (thanks again!), adjusted it and updated tests and the README file. The provider logs the values for now for testing purposes. When you test the PR locally, you can check the logs to verify that the values are correct.

This PR does not contain any frontend changes or changes to the aggregated metrics card, I will do this in a separate PR. This means that if you test these changes locally, the cards will not be showing up correctly in the UI, example here:

An example of a config for local testing:

scorecard:
  plugins:
    github:
      files_check:
        files:
          - readme-correct: "README.md"
          - i18guide-correct: "docs/backstage-i18n-guide.md"
          - readme-incorrect: "./README.md"
          - i18guide-incorrect: "/docs/backstage-i18n-guide.md"
        schedule:  # Now works! Matches provider ID "github.files_check"
          frequency: { minutes: 5 }
          timeout: { minutes: 10 }
          initialDelay: { seconds: 5 }

Example of a console log for fetched data:

So to summarize, the changes that will be added in a future PR will include:

• frontend changes
• any changes needed for the aggregated metrics card
• e2e tests
• changesets

I'll be happy for any feedback, thank you in advance!

✔️ Checklist

• A changeset describing the change and affected packages. (more info)
• Added or Updated documentation
• Tests for new functionality and regression tests for bug fixes
• Screenshots attached (for UI changes)

[imykhno]

Thank you! I have tested this locally with various files—including README.md, LICENSE, and CODEOWNERS— and configured the schedule for the files_check metrics. I can confirm that the functionality works as expected.