feat: add option to read user-supplied key string in ssh_bind_options_set()

Signed-off-by: Debanga Sarma <deb737@proton.me>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>

include/libssh/server.h

@@ -58,6 +58,7 @@ enum ssh_bind_options_e {
     SSH_BIND_OPTIONS_PROCESS_CONFIG,
     SSH_BIND_OPTIONS_MODULI,
     SSH_BIND_OPTIONS_RSA_MIN_SIZE,
+    SSH_BIND_OPTIONS_IMPORT_KEY_STR,
 };
 
 typedef struct ssh_bind_struct* ssh_bind;