board/common: Make it easier to access the CLI

- Create a shell alias, 'cli'
- Add an sshd subsystem, 'cli'

board/common/rootfs/etc/profile.d/convenience.sh

@@ -16,3 +16,4 @@ alias ipaddr='ip addr'
 alias iplink='ip link'
 alias bridge='bridge --color=auto'
 alias setup='setup -c'
+alias cli='clixon_cli'

board/common/rootfs/etc/ssh/sshd_config.d/cli.conf

@@ -0,0 +1 @@
+Subsystem cli /usr/bin/clixon_cli