Support remote Multipass daemons

**What are you trying to do?**

I'm using multipass with a remote server from a small netbook using roadwarrior networking. And I need to execute commands like "shell" from my local device to the remote server. However, the current implementation (hidden/unsupported MULTIPASS_SERVER_ADDRESS) doesn't support this.

**What's your proposed solution?**
It's necessary to support all commands with remote clients.

**Additional context**
Without this _basic_ functionality the remote execution is useless.

Start by tracing the hidden MULTIPASS_SERVER_ADDRESS handling and how the shell command reaches a remote server. Define the remote-client behavior for every command, then verify that commands such as shell execute successfully through a remote Multipass daemon.

Written by the indexing model from the issue text.