Use rsync to sync folder with libvirt provider

[roblabla]

smb sync folder method only works on windows and MacOS host machines, according to this, causing the build to fail. Using rsync works without issues.

[rgl]

I'm using it in linux too, but I have to manually apply hashicorp/vagrant#9948 (using the https://patch-diff.githubusercontent.com/raw/hashicorp/vagrant/pull/9948.patch file) to my local vagrant installation.

I still haven't gotten around for fleshing out the unit tests needed for that PR to be merged in vagrant.

The environment in this repo copies a file to the host vagrant share:

windows-domain-controller-vagrant/provision/ca.ps1

Lines 32 to 36 in 29c54af

	# export the CA certificate to the Vagrant project directory, so it can be used by other machines.
	mkdir -Force C:\vagrant\tmp | Out-Null
	dir Cert:\LocalMachine\My -DnsName $caCommonName `
	| Export-Certificate -FilePath "C:\vagrant\tmp\$($caCommonName -replace ' ','').der" `
	| Out-Null

That file is used by other environments (e.g. https://github.com/rgl/gitlab-vagrant), so I have to keep using SMB.

Though, I can merge the PR when you change it to be something alike: Actually this will not work... the ubuntu test node also needs to access tmp/ExampleEnterpriseRootCA.der, so this is a no go for me.

if ENV['VAGRANT_SMB_PASSWORD']
  ... smb line
else
  ... rsync line
end

[roblabla]

Ah, awesome. I don't personally use the ubuntu test node, so I guess I'll keep doing this locally.

Having a bit in the README to let people know they need a custom vagrant build with hashicorp/vagrant#9948 on linux would probably be helpful ^^.