add client script: shows count of characters remaining in a field

[Rajat32-op]

PR Description:

Adds a Client Script that provides real-time character count feedback for text fields in ServiceNow forms. Shows remaining characters with visual indicators (info/warning/error) to help users stay within field limits.

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
• I've included only files relevant to the changes described in the PR title and description
• 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)
• I've disclosed use of ES2021 features (if applicable)
• I've tested my code snippets in a ServiceNow environment (where possible)

Repository Structure Compliance

• I've placed my code snippet(s) in one of the required top-level categories:
  • Core ServiceNow APIs/
  • Server-Side Components/
  • Client-Side Components/
  • Modern Development/
  • Integration/
  • Specialized Areas/
• I've used appropriate sub-categories within the top-level categories
• Each code snippet has its own folder with a descriptive name

Documentation

• I've included a README.md file for each code snippet
• The README.md includes:
  • Description of the code snippet functionality
  • Usage instructions or examples
  • Any prerequisites or dependencies
  • (Optional) Screenshots or diagrams if helpful

Restrictions

• My PR does not include XML exports of ServiceNow records
• My PR does not contain sensitive information (passwords, API keys, tokens)
• My PR does not include changes that fall outside the described scope

[mskoddow]

The script could be enhanced in some points (e.g. check if the related field is really visible on the form), but it already provides great value. Therefore I'm going to approve it.

[mskoddow]

Thank you for your contribution. Your story completion has been reviewed and approved. Basically, the script could be enhanced in some points (e.g. check if the related field is really visible on the form), but it already provides great value. Glad to have you as part of Hacktoberfest with ServiceNow and hope to see more from you!