feat: Add -webkitMaskImage for cross-browser gradient mask support

[JeffBeltran]

This PR enhances the existing gradient mask utility in our Tailwind plugin by adding the -webkitMaskImage property. This ensures that the gradient mask feature works seamlessly across WebKit-based browsers like Chrome and Safari.

Changes:

• Added -webkitMaskImage property alongside the existing maskImage in the utility generation code.

Why this change?

• Provides better cross-browser support, specifically targeting WebKit-based browsers.
• Ensures a more robust and future-proof solution for handling CSS masking.

Testing:

• Verified the gradient mask functionality in Chrome, Safari, and Firefox to ensure compatibility.