Expand the apt provider to support virtual packages
https://github.com/puppetlabs/puppet/pull/7701
Merged to 6.4.x in https://github.com/puppetlabs/puppet/commit/0eb47ec1ca2aee34e6b88fb637e89f62cefd0b1c
Passed master CI d984877b2674c89407dedf47307475e22b943e60