Remove Duplicate Filelists

Summary:
Every AtCoreInstance was getting a copy of the file list. This will remove the need to have the instance
get a copy.

Reviewers: patrickelectric, tcanabrava, laysrodrigues

Reviewed By: patrickelectric, laysrodrigues

Subscribers: Atelier: General Development

Tags: Atelier: General Development

Differential Revision: https://phabricator.kde.org/D12653