Windows Sandbox configuration: Support relative paths in mapped folders

[AnthonyMastrean]

Suggested new feature or improvement

For mapped folders, the documentation says:

At this time, relative paths aren't supported.

https://learn.microsoft.com/en-us/windows/security/application-security/application-isolation/windows-sandbox/windows-sandbox-configure-using-wsb-file#mapped-folders

It would be nice if relative paths were supported.

Scenario

Without relative path support, WSB files are basically useless in team development scenarios, without requiring fixed paths across development machines and even that prevents certain development workflows like Git worktrees (which require changing the path).

Additional details

No response