feat(ssh): complete RequiredRSASize (#1064)

1. The RequiredRSASize option was added in openssh/openssh-portable@54b333d .
2. RHEL 9.1 changed minimum RSA key size to 2048 by default, broke connections
   to old SSH servers.
3. Fedora Linux sync'ed the change from RHEL 9.1. See:
https://packages.fedoraproject.org/pkgs/openssh/openssh-server/fedora-37.html

completions/ssh

@@ -73,11 +73,11 @@ _comp_xfunc_ssh_options()
         PasswordAuthentication PermitLocalCommand PKCS11Provider Port
         PreferredAuthentications ProxyCommand ProxyJump ProxyUseFdpass
         PubkeyAcceptedAlgorithms PubkeyAuthentication RekeyLimit RemoteCommand
-        RemoteForward RequestTTY RevokedHostKeys SecurityKeyProvider SendEnv
-        ServerAliveCountMax ServerAliveInterval SetEnv StreamLocalBindMask
-        StreamLocalBindUnlink StrictHostKeyChecking SyslogFacility TCPKeepAlive
-        Tunnel TunnelDevice UpdateHostKeys User UserKnownHostsFile
-        VerifyHostKeyDNS VisualHostKey XAuthLocation
+        RemoteForward RequestTTY RequiredRSASize RevokedHostKeys
+        SecurityKeyProvider SendEnv ServerAliveCountMax ServerAliveInterval
+        SetEnv StreamLocalBindMask StreamLocalBindUnlink StrictHostKeyChecking
+        SyslogFacility TCPKeepAlive Tunnel TunnelDevice UpdateHostKeys User
+        UserKnownHostsFile VerifyHostKeyDNS VisualHostKey XAuthLocation
     )
     # Selected old ones
     opts+=(
@@ -210,6 +210,9 @@ _comp_cmd_ssh__suboption()
         requesttty)
             _comp_compgen -- -W 'no yes force auto'
             ;;
+        requiredrsasize)
+            _comp_compgen -- -W '1024 2048 3072 4096 7680 15360'
+            ;;
         stricthostkeychecking)
             _comp_compgen -- -W 'accept-new ask no off'
             ;;