- Spec cleanup.

- added https://github.com/dtschump/gmic/commit/56f7340ecb1fbbe6fce87d0a5c8d35dd13359577.patch
make it search in /usr/share/gmic/ with all clients.

- prepare gimp 3 support
- install also the denoise data file
- introduce a new gmic-data subpackage and require it from all the
frontends so we can access it more easily once this is resolved:
https://discuss.pixls.us/t/fixing-more-things-in-gmic-packaging/28894
- make bash-completion noarch

- move shared options for all the gmic-qt versions into a define
to reduce duplication

- Rework patches:
- drop old patches with git generated copies:
- 5e34754707b78358ef818d542d1e81d008bb2d12.patch
- dont-set-gmic_build.patch
- gmic-krita5.patch
- make-build-without-gmic-cpp.patch
- new patches:
- gmic-make-build-without-gmic-cpp.patch
- gmic-qt-make-it-work-without-gmic-cpp.patch
- krita5.patch
- Update krita patch so we can apply it as normal patch without
breaking other gmic-qt instances

- Remove unneeded BuildRequires fftw3-devel and cmake(KF5CoreAddons)