Add Client Script: Visual Mandatory Field Highlighter with Red Border

[Rajat32-op]

PR Description:

This PR adds a Client Script that provides visual highlighting for empty mandatory fields on ServiceNow forms. The script automatically adds red borders and subtle shadows to mandatory fields that are not filled, helping users quickly identify which required fields need attention.

Pull Request Checklist

Overview

• I have read and understood the CONTRIBUTING.md guidelines
• My pull request has a descriptive title that accurately reflects the changes
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• I've created a new branch in my forked repository for this contribution

Code Quality

• My code is relevant to ServiceNow developers
• My code snippets expand meaningfully on official ServiceNow documentation (if applicable)
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• I've tested my code snippets in a ServiceNow environment (where possible)

Repository Structure Compliance

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  • Server-Side Components/
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• My PR does not include changes that fall outside the described scope

[ivan-betev]

Thank you for your contribution and idea, however as I can see you are using non existing methods

g_form.addElementChangeListener

In addition, the DOM manipulation is a bad practice.

Please fix it and resubmit or reopen.