Added support for content level 2 in widget extensions

What does this MR do and why?

Adds support for content level 2 within merge request widget extensions.

Creates a method, generateText, that takes a string with sprintf tags and then replaces them based on the styles that we allow within the extensions.

Screenshots or screen recordings

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Closes #341046 (closed)