Add reusable date helper functions

[Emmynem]

PR Description:

Summary

This PR adds a set of date utility functions for use in ServiceNow Script Includes, Business Rules, and Client Scripts.
The helpers provide consistent, reusable formatting for dates and timestamps.

Added Functions

• getTodayISO() → Returns today's date in YYYY-MM-DD format
• getTodayReadable() → Returns today's date in human-readable form (e.g., Sat Oct 04 2025)
• getCurrentYear() → Returns the current year as a number
• formatUnixTimestamp(unixSeconds) → Converts UNIX timestamp to { fullDateTime, date, time }
• formatDateTime(jsDate) → Converts JS Date/string into "YYYY-MM-DD HH:mm:ss"

Why

Working with dates in ServiceNow often requires repeated formatting. These helpers simplify formatting for logs, audit fields, and UI messages.

Example Usage

gs.info(getTodayISO());          // "2025-10-04"
gs.info(getTodayReadable());     // "Sat Oct 04 2025"
gs.info(getCurrentYear());       // 2025
gs.info(formatUnixTimestamp(1696425600));
// { fullDateTime: "Sun Oct 04 2025 at 12:00:00 AM", date: "Sun Oct 04 2025", time: "12:00:00 AM" }

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

[am-shakeel]

Thanks for your submission. It appears that this pull request contains more files than described in the title. Please review and update the pull request to either remove the extra/unintended files or to update the description to be more comprehensive. Ensure your contributions are meaningful and adhere to the project’s standards. You can create a new branch on your forked repository to avoid accidental inclusions of new commits in the future. Closing this for now. Once you make additional changes, feel free to re-open this Pull Request or create a new one.