feature request: hook effects in xiu hooks

**is your feature request related to a problem? Please describe.**
I'm making a hook that [reencodes FLAC to Opus on upload](https://github.com/minipps/copyparty-hooks/blob/main/lossless_to_opus.py). For this I chose xiu since I want to do this after full file uploads and I want to be able to delete the old FLAC and re-index the new OGG after upload, however, it seems like xiu uses `runihook` instead of `runhook` which doesn't support hook effects

**Describe the idea / solution you'd like**
Add [hook effects](https://github.com/9001/copyparty/blob/fface524c3463918677bd01a6aff7d09dbbbc29d/docs/devnotes.md#hook-effects) to xiu too :)

**Describe any alternatives you've considered**
for now I'm just using a lower scan period for indexing and os.unlink() to delete the file manually from inside my hook, although this is obviously way worse.