isWindowsNetworkDrive is not set to `true` for WSL2

[bwallberg]

For WSL2 the filesystem is mounted as a network drive eg "\\wsl.localhost\\Ubuntu\\home\\me\\assets\\ldtk"l however this doesn't seem to be properly detected so the error that shows up in eg. LDTK is the permissions error instead of the network drives not supported error.

I'm haven't done much haxe so I'm unsure if I'll be able to make a PR.