Set Permissions of Resource Disk about walinuxagent

[ahmetb]

@kemhof I'm assuming this issue is about changing the owner/group of the mountpoints.

I believe we are consistent with Windows (and other cloud providers') behavior here by letting only root write to the resource disk (/mnt or /mnt/resource).

If you need to customize it for yourself, you can have a startup script (or a cloud-init/cloud-config script through CustomData field on the virtual machine) to chmod/chgrp these mountpoints.