Add JXL support

This is an experimental extension that converts any JXL (JPEG XL) image file in the page to WEBP. It uses the following code for conversion: * https://github.com/niutech/jxl.js You can find my fork here: * https://bit.ly/jxl-as-Chrome-extension Limitations: * Conversion may take a couple of seconds, especially for large images. * No support for animated JXL files. Only the first frame is rendered. * May cause some pages to not load at all. If this happens, please uninstall the extension. This is a work in progress. More explanation on use cases, tips, and workarounds here: * https://r360v.blogspot.com/p/jace.html