Support more than one alias in last_file mode (#1)

There is an open issue with the upstream repo (necojackarc#115) where the behavior when turning on last_files_match_only only matches one alias, even if mutliple files have been edited.

This is a different behavior than GitHub's codeowners file which the setting seeks to emulate.

This PR adds a per file check to the last match, allowing each file to add one alias assuming that that file matches a glob pattern inside the codereviewers yaml file.