Consider a different location for Multipass files on macOS

I imagine that, like me, most mac users of virtualization choose to exclude VM disk images from Time Machine backups. Multipass on macOS puts its files in /var/root/Library/Application Support/multipassd/. There are problems with this:

1. It is undocumented, and users have to go digging to find out where these images are in order to add them to their TM excluded directory list.

2. You can't get there in the Finder. To exclude multipass' folders, you either have to do some ninja "sudo open" stuff or use the tmutil command line (i.e. "sudo tmutil addexclusion -p /var/root/Library/Application\ Support/multipassd").

3. If a user wants to use TM to backup their multipass images, recovery is extremely awkward since macOS has this location pretty locked down.

I can see that you're trying to keep things really simple and assume this is the reason to keep multipass' disk images out of a folder in the user's home directory. Perhaps somewhere like under /opt instead? XQuartz keeps its stuff there.

Really liking multipass! I've been playing with it a lot lately, but needed to fire up something new in VirtualBox yesterday and thought, "Oh my god, this is taking SOOO long compared to multipass."

The issue concerns Multipass files at /var/root/Library/Application Support/multipassd/ on macOS and their interaction with Time Machine. Start by reviewing the current macOS storage behavior and the 48-comment discussion; done requires an agreed, supported location that makes exclusion and recovery practical.

Written by the indexing model from the issue text.