Feature request: WebP support for Convert Image Format

**Is your feature request related to a problem? Please describe.**
I have a folder of WebP files that I would like to convert to JPEG or PNG. WebP is a popular image format used on the web, but can be difficult to use in other applications without converting it to something else.

**Describe the solution you'd like**
Multimedia > Convert Image Format does not work with the WebP format as input. I would like to be able to input WebP, and output a different format.

**Additional context**
`/src/core/operations/ConvertImageFormat.mjs`

It looks like the image processing library, Jimp, does not support WebP by default. But a custom jimp for WebP can be created with a plugin:
https://jimp-dev.github.io/jimp/guides/webp/