options: Added an option to set server HostKey algorithms
The added option SSH_BIND_OPTIONS_HOSTKEY_ALGORITHMS allows restricting
the signature algorithms to offer to the client for host authentication.
The list set is used as a filter of allowed algorithms.
First a list of possible signature algorithms to offer is created from
the keys set and then such list is filtered against the allowed
Signed-off-by: Anderson Toshiyuki Sasaki <email@example.com>
Reviewed-by: Jakub Jelen <firstname.lastname@example.org>