gnome: generate cpp gresource source in cpp projects
gnome: generate cpp gresource source in cpp projects

Closes #7839

jpakkane/meson,jpakkane/meson,jpakkane/meson,pexip/meson,QuLogic/meson,pexip/meson,pexip/meson,mesonbuild/meson,jpakkane/meson,pexip/meson,mesonbuild/meson,pexip/meson,jpakkane/meson,jpakkane/meson,mesonbuild/meson,jpakkane/meson,pexip/meson,QuLogic/meson,jpakkane/meson,mesonbuild/meson,mesonbuild/meson,QuLogic/meson,QuLogic/meson,pexip/meson,mesonbuild/meson,pexip/meson,jpakkane/meson,QuLogic/meson,mesonbuild/meson,QuLogic/meson,QuLogic/meson,mesonbuild/meson,pexip/meson,pexip/meson,QuLogic/meson,QuLogic/meson,mesonbuild/meson,mesonbuild/meson