refactor(modal): Add onModalScroll prop to Modal component

[diogomateus]

What this PR does

Add onModalScroll prop to Modal component.

Checklist:

• I reviewed my own code
• The changes align with the designs I received
  Or give a reason why this does not apply:
• I have attached screenshot(s), video(s) or gif(s) showing that the solution is working as expected
  Or give a reason why this does not apply:
• I have updated the task(s) status on Linear
• All new media is optimized (images, gifs, videos)

Browser support

My code works in the following browsers:

• Firefox
• Chrome
• Safari
• Edge