Adds new how-to on running GitLab locally in a VM
Adds a new how-to doc on how to run GitLab EE locally in a Vagrant-managed VM.
Taken from https://ops.gitlab.net/gitlab-com/gl-infra/deploy-tooling/-/merge_requests/359#note_112979, I used this when testing Ansible playbook changes in deploy-tooling
and thought it'd be a useful guide generally.