vendor/OPENSSH: upgrade from 8.8p1 top 9.1p1

vendor/OPENSSH: upgrade from 8.8p1 top 9.1p1

Summary of notable changes:

 * sshd(8): fix an integer overflow in the user authentication path
 * ssh(1), sshd(8), ssh-add(1), ssh-agent(1): add a system for
   restricting forwarding and use of keys added to ssh-agent(1)
 * ssh(1): unbreak hostbased auth using RSA keys.
 * sshd(8): fix truncation in rhosts/shosts path construction.
 * ssh(1), sshd(8): use the hybrid Streamlined NTRU Prime + x25519 key
   exchange method by default ("sntrup761x25519-sha512@openssh.com").
   The NTRU algorithm is believed to resist attacks enabled by future
   quantum computers.
 * sftp(1): add a "cp" command to allow the sftp client to perform
   server-side file copies.
 * scp(1): fix a memory leak in argument processing.
 * ssh-keygen(1): double free() in error path of file hashing step in
   signing/verify code;
 * ssh-keyscan(1): fix a one-byte overflow in SSH- banner processing.
   Reported by Qualys
 * sftp-server(8): add a "users-groups-by-id@openssh.com" extension
   request that allows the client to obtain user/group names that
   correspond to a set of uids/gids.
 * sshd(8): improve logging of errors when opening authorized_keys
   files.

For a detailed list of changes, please check:
https://www.openssh.com/releasenotes.html