make plugins load installed data from resources if not found in filesystem
Summary: Store plugin data in qt5's resource system
Test Plan: Compile, remove file from 'regular' system locations, ensure related feature still functions
Reviewers: kfunk, apol, mwolff
Reviewed By: apol, mwolff
Subscribers: apol, kdevelop-devel
Projects: KDevelop
Differential Revision: https://phabricator.kde.org/D528