Parse private keys for V3 onion services when included in links

Onionshare 2.4 has just been released, and has switched from using HTTP auth to V3 private keys. As such, users must manually enter the private key in the V3 auth wingpanel in order to view a protected file:

As per n8fr8's suggestion, it would be great it Tor Browser would support the parsing of keys placed directly in the link instead, e.g.

http://oy5oaslxxzwib7fsjaiz5mjeyg3ziwdmiyeotpjw6etxi722pn7pqsyd.onion?key=K3N3N3U3BURJW46HZEZV2LZHBPKEFAGVN6DPC7TY6FHWXT7RLRAQ

Thereby pre-filling or silently completing the V3 auth wingpanel entirely.

(Unless there's a good reason why we shouldn't do this @sysrqb/@richard?)