Make VM edit operations nonblocking in macOS

[ideologysec]

Please make the popup window for editing VMs non-blocking and ideally a separate window.

I cannot start or manage other VMs while I am (for example) reclaiming space on a virtual disk, unless I resort to the utmctl commandline, which while possible is not the most user-friendly experience.

[ideologysec]

Related: #6300

[osy]

While this sounds like a trivial change, it actually requires massive changes under the hood. Fundamentally, UTM was first designed for iOS meaning that there is always one "primary" view active at a time.