Migrate roles to hiera_include

Replace the use of imported manifests with hiera_include() and a hiera
config file that is managed by the `vagrant *-role` commands.

* Move manifests/roles/*.pp to modules/role/manifests/*.pp
* Move templates and files to role module
* Update mediawiki-vagrant plugin to manipulate vagrant-managed.yaml
  hiera file
* Migrate existing manifests.d/vagrant-managed.pp to
  vagrant-managed.yaml
* Merge manifests/base.pp into manifests/site.pp
* Add common.yaml hiera file

Bug: 67214
Change-Id: Ieafa5882eb4f0110c99afcbcbd6d068d42e5fea2