project plugin: first try at adding support for the CMake file API

This commit adds support for the cmake file API to kate (see https://cmake.org/cmake/help/v3.14/manual/cmake-file-api.7.html). If we have a cmake build tree, it creates the necessary query files, reruns cmake. parses the resulting json files and creates a kate project from them, including the project name, targetsfor the build-plugin and the list of files.