Support running dnsmasq on a different port

**Describe the bug**
failed: cannot connect to the multipass socket

**To Reproduce**
OS: Ubunut 22.04 - fresh install
How, and what happened?
1. `multipass list`
`list failed: cannot connect to the multipass socket`

port 53 is allocated by named/systemd-resolved when Ubuntu is freshly installed. so the multipass fails to work.

maybe using different port would help?

Start by reproducing `multipass list` on a fresh Ubuntu 22.04 installation where `named` or `systemd-resolved` occupies port 53, then trace how Multipass starts and configures dnsmasq. Done means Multipass can operate when port 53 is unavailable, with the selected port configured consistently and the socket connection succeeding.

Written by the indexing model from the issue text.