Add content_catalog.json (similar to llms-full.txt) (#1299)

* Add script to generate content_catalog.json (similar to llms-full.txt)

As a cleanup, this PR also removes the old apply_image_effects.py and
the accompanying blurmask.png.

* Update package-lock.json

* Create content_catalog.json

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Co-authored-by: Debbie Matthews <[email protected]>

Author: sfc-gh-tteixeira