Add magnet url from info hash

[trim21]

Discussed in https://github.com/jesec/flood/discussions/520

^{Originally posted by joshhhhyyyy February 27, 2022} An option to add a torrent from the infohash. I tried doing this on my instance but it crashed and said unable to connect to transmission, so i presume this is not a feature thats implemented.

system info (if u need it): running flood on debian 11 bullseye with transmission. regular torrent magnet links work.

Please reference This issue for further context as the issue throughly summarises all my points.