Build server VFAT partition for Windows SDK

[chrmod]

For some reason windows SDK has to be mounted to docker a volume with VFAT partition.

Issue is this partition is mounted by hand on magrathea build server and has to be recreated after every reboot.

We should find a more robust way to deal with it.

[sammacbeth]

For some reason

This is because the SDK needs to be in a case-insensitive filesystem. As we cannot create and mount filesystems in docker itself, we must mount this filesystem on the host and then expose it to docker as a volume.