Feature request: add thumbhash support in `meta` api

[everyx]

ThumbHash is a a very compact representation of an image placeholder, it would be great to add it support to the meta API. :)

[chladog]

Would be super useful! 💯 But probably as filter/path parameter would be even better, no need to fetch metadata and extracting from json, just /thumb/path2img or thumb() filter. And you could make a thumb of processed images as well this way! (E.g. you get thumb of grayscaled image, hue-shifted or cropped one)