Adds support for extra_filerefs=salt://path1,salt://path2 CLI arg to include *template*-referenced files (ie: includes) in thin data package sent to minion during salt-ssh.

Fixes issue #9878
Merge pull request #13794 from sandbender/extra_filerefs

Adds support for extra_filerefs=salt://path1,salt://path2 CLI arg to inc...