Add command for setting up SSH config for simple access for other applications

[leighmcculloch]

What are you trying to do?
multipass shell is a handy command when needing to get shell access, but whenever using other applications that require using SSH, it is much more inconvenient to get access. For example, if I start a multipass instance and want to SSH to it with VSCode, I need to have setup an ~/.ssh/config entry that has the IP, username, and references the identity (private key) file that is located at /var/root/Library/Application Support/multipassd/ssh-keys on macOS.

What's your proposed solution?
Add a command, such as multipass sshconfig that mutates the system .ssh/config writing in a config entry that has host name equal to the multipass instance name, and has its IP, username, and identity file configured. Something like:

Host primary
    HostName 172.16.16.7
    User ubuntu
    IdentityFile /var/root/Library/Application Support/multipassd/ssh-keys
    IdentitiesOnly yes

Additional context
N/A

[Saviq]

Hey @leighmcculloch yup, we have something like this planned.

Duplicate of #1957