After testing the Image Effects, it was decided to proceed first with pixels. In this PR, we revert the offset and size fields to pixels. Also, an issue with the edit asset page was fixed.

Approach

• Prepared the fields to use pixels.
• Added a slug to the edit_page settings.

QA notes

• Go to the edit effects page of an asset and ensure the effect can be configured using pixels
• Ensure the front-end renders the effects correctly.