This commit creates a custom `read_dhcp_servers` method in the VirtualBox 6.1 driver to handle changes made in the ouput of `VBoxManage list dhcpservers`. Tests for VirtualBox 6.1+ can no longer use the shared examples for the VirtualBox 4.x driver, because the `read_dhcp_servers` change is not backwards compatible. This commit also creates the boilerplate for a VirtualBox 6.x shared example in case we want to put tests there in the future.
Vagrant Core Plugins
These are plugins that ship with Vagrant. Vagrant core uses its own plugin system to power a lot of the core pieces that ship with Vagrant. Each plugin will have its own README which explains its specific role.