Better JXL integration in XnviewMP

[simon]

Hi,
2 suggestions for a better integration of jxl files

1) replace the add-on 'exiftool.exe' by a more recent version (versions <= 12.60 are unable to read brotli-compressed metadata, which is the usual way metadata are stored in jxl files).

2) add (both in browser and viewer modes) an entry in the 'jpeg-lossless transformation' menu for lossless transcoding to jxl. Currently, it is possible to losslessly save or export jpg files as jxl files with quality set to lossless, but this results in huge files (2-3X larger than the original jpg) whereas direct lossless transcoding would make it possible to spare about 20% space.

thanks
simon