Use images instead of giant dataURLs for module tests

[harshkhandeparkar]

Please describe the problem (or idea)

Module tests currently store the expected output image as a dataURL in a variable. Instead, we need to load the image dynamically from a directory.

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[root00198]

Okay I am on it...Once my GIF test PR got merge, because otherwise some file will conflict if I start working now...

[jywarren]

Pretty good solution just needs a rebase here: #1604