contrib: bash_completion.d: install, fix dist

dist diff:

-zfs-2.1.99/contrib/bash_completion.d/zfs

install diff:

+destdir/usr/local/etc/bash_completion.d
+destdir/usr/local/etc/bash_completion.d/zfs

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #13316