[Windows] Evaluate creating custom logic for GUEST username

### Description

Windows username returned often is made of multiple parts (includes domain name), which prevents it from being used as a username in Unix environment.

This is a followup to https://github.com/lima-vm/lima/pull/3378#issuecomment-2748965335

The idea is to evaluate at least major common cases:
* local user
* MS account user
* Active Directory user

If there be an opportunity to evaluate some other Domain controller integration it should be considered as a plus.

This has low prio and no urgency as the machines are functional with a fallback user, this is a task to evaluate if it is reasonable to improve UX to make it closer to one on other platforms.