With Qt Creator 7 plugin qmake support was removed and only cmake is supported.
I've tried to move my plugin to cmake, but there are no plugin cmake files in
`qt5-creator-plugin-devel` (or `qt5-creator`) packages.

qt.io binaries have `lib/cmake/QtCreator` directory with
`QtCreatorConfig.cmake` and other cmake files, but there is no similar
directory (`/usr/lib64/cmake/qt5-creator` or `/usr/lib64/cmake/QtCreator` or
`/usr/lib64/cmake/Qt5Creator`) in our RPMs.

So I can't build even "empty" plugin just created by QtCreator's wizard.

I've tried to dig slightly into it (almost zero cmake knowledge), on build
stage there is cmake folder with `QtCreatorConfig.cmake` in it created by
`src/CMakeLists.txt` but for some reason they are not present in install
(though they seem should be there as `install()` is present in that
CMakeLists).

It'd be nice to have them in RPMs to be able to build Qt Creator plugins.