Refactor to embrace a cmake server import backend
Summary:
Allow using cmake -E server rather than the compilecommands json files we use
nowadays.
Test Plan:
Opened few projects locally successfully. Needs a patch I submitted to upstream
cmake and won't be released until 3.7.2 is out.
Reviewers: kfunk, mwolff, KDevelop
Reviewed By: mwolff, KDevelop
Subscribers: mwolff, antonanikin, arrowdodger, kfunk, kdevelop-devel
Tags: KDevelop
Differential Revision: https://phabricator.kde.org/D4095