Allow passing the --xmp-sidecar option

[alcroito]

v1.25.0 of icloud_photos_downloader has introduced an --xmp-sidecar flag to generate sidecar .xmp files.
It would be nice to be able to enable it when using icloudpd.

[boredazfcuk]

I tried to convert this to a discussion as it doesn't belong here, but the it seems the process failed. I'll try again tomorrow when I have access to my laptop,

[boredazfcuk]

I've had a quick look at this, but I don't actually have the means to generate any raw files to test downloading the sidecar files. I don't knwo how icloud_photos_downloader handles these. For example, when deleting a live photo, icloud_photos_downloader only deletes the HEIC file and not the accompanying HEIC_HEVC.MOV file which accompanies it. I don't know if the same is true for the sidecar files.