libzfs: add keylocation=https://, backed by fetch(3) or libcurl
Add support for http and https to the keylocation properly to
allow encryption keys to be fetched from the specified URL.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Issue #9543
Closes #9947
Closes #11956