Create mergerfs.findfile

[id628]

This script tells you which drive holds the file you're looking for. It also warns you if there are multiple copies in different drives.

[id628]

@trapexit I have been using mergerfs (with Snapraid) for many years now, and often I needed to know which physical drive a file was actually stored on. Recently, I started a file migration project that made this crucial to me. So using the knowledge exposed by mergerfs.consolidate, I created this script to identify the drive mergerfs found the file on, and also if it's duplicated on other drives (redundant, I know, but helpful in my case).

[mbeware]

I was about to create a feature request for this functionnality. Thank you for creating it!

(I rewrote the next sentence many time to not make it as a critique or something negative as I could. It is still not as tame as I wished. sorry)
I think this pull request might get more chances of being included if the changes to the documentation was included.