Feature request: Add perceptual hashing

**Is your feature request related to a problem? Please describe.**
There are two fuzzy hashing functions already available on CyberChef (SSDEEP and CTPH) and would be nice to also add a perceptual hashing one; ideally that works on multiple input types (phash can be applied on images, audio, video and text)

**Describe the solution you'd like**
A function to calculate the perceptual hash of an input image or text

**Describe alternatives you've considered**
phash online website has a demo, but only works for images http://phash.org/demo/

**Additional context**
A perceptual hash is a fingerprint based on the image input, that can be used to compare images by calculating the [Hamming distance](http://en.wikipedia.org/wiki/Hamming_distance)

The issue names no files, entry points, or tests. Start by locating the existing SSDEEP and CTPH operations and determine how CyberChef handles image and text inputs; done requires a defined perceptual-hashing scope, supported input types, and verification coverage.

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