ci: combine header checks into workflow with PR comment

[se-bastiaan]

✍️ Description

This pull request include changes to the GitHub Actions workflows for validating shell scripts.

Consolidation of validation workflows:

• .github/check-script.yml: Removed the workflow that checked shell scripts for specific lines and executable permissions. This workflow was in the wrong folder and therefore never executed.
• .github/workflows/check-metadata.yml: Removed the workflow that checked metadata lines in shell scripts. This workflow uses the wrong paths and was therefore never executed.

Introduction of a new validation workflow:

This pull request consolidates and improves the script validation workflows by combining multiple checks into a single comprehensive validation workflow. The changes remove redundant workflows and introduce a new workflow that performs various checks on shell scripts.

Consolidation of script validation workflows:

• .github/workflows/validate-scripts.yml: Added a new workflow that performs multiple checks on shell scripts, including:
  • Validating the presence and correctness of the source line.
  • Checking for executable permissions.
  • Ensuring the presence and correctness of metadata headers (copyright, author, license, and source).
  • Posting results and comments on pull requests.

It might be good to note that a lot of files to not comply with the checks in this workflow. So any new PRs will fail and should be fixed before merging.

Like #1239 the comment placed by the workflow has start and end tags, to make it possible to add more information to a single comment from other workflows. In code it looks like:

<!-- validate-scripts-start -->
### Script validation

:rocket: All changed shell scripts passed validation!


<!-- validate-scripts-end -->

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Please remove unneeded lines!

• Related Issue: # (issue number, if applicable)
• Related PR: # (if applicable)
• Related Discussion: (if applicable)

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🛠️ Type of Change

Please check the relevant options:

• Bug fix (non-breaking change that resolves an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change unexpectedly)
• New script (a fully functional and thoroughly tested script or set of scripts)

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✅ Prerequisites

The following steps must be completed for the pull request to be considered:

• Self-review performed (I have reviewed my code to ensure it follows established patterns and conventions.)
• Testing performed (I have thoroughly tested my changes and verified expected functionality.)
• Documentation updated (I have updated any relevant documentation)

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📋 Additional Information (optional)

Tested in se-bastiaan#2