added support for new line break in stampController

[saikumarjetti]

Description

This PR fixes the issue where the stampText feature was showing "\n" as plain text instead of interpreting it as line breaks.

Summary of Changes:

• Added support for handling line breaks in stampText, splitting the input text into multiple lines wherever \n is encountered.
• Calculated line height using the font's ascent and descent metrics, ensuring proper spacing between lines regardless of font size or style.

Closes #(2345)

Checklist

• I have read the Contribution Guidelines
• I have performed a self-review of my own code
• I have attached images of the change if it is UI based
• I have commented my code, particularly in hard-to-understand areas
• If my code has heavily changed functionality I have updated relevant docs on Stirling-PDFs doc repo
• My changes generate no new warnings
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