Remove old `forward_port` method for configuration. Use `network`
Booting new VirtualBox VM should check for port collisions
Explicitly set error handling for port collision on resume
Remove network validation on config. We'll re-add this later.
VirtualBox forwarding port uses new `network` calls
Temporarily disable Network action while it is broken
Fix ordering of forwarded_port call
Make box creation not cross filesystems.

This will cause issues on modern linux which uses a tmpfs-backed tmpdir.
Rework v1 forward_port call to append forward port networks
New Network VirtualBox middleware to handle the changes.

Note this is a WIP (hence committed on a branch)
Check port collisions now uses the new high-level networking
Forwarded ports use the new high-level configuration
Configure networks on the VM
Add support for bridged networks again
Support mac address and nic_type for host only networks
Remove the old networking code
Util::ScopedHashOverride
Use scoped hash overrides for high-level config
Forwarded ports allow for scoped hash overrides
Raise proper error if there aren't any NIC slots available