[packaging] Fix CMake devel files packaging
The shipped QtQml CMake config file includes all nearby CMake files with plugins. We don't want to pull the plugins with the base devel package, so move the plugins CMake files to their own devel package.
The shipped QtQml CMake config file includes all nearby CMake files with plugins. We don't want to pull the plugins with the base devel package, so move the plugins CMake files to their own devel package.