support for the contents/ directory of kpackage to be
compressed in an rcc file, new cmake macro
kpackage_install_bundled_package which generates it,
the old install package is unaltered for better retrocompatibility

most of plasma ui works correctly, plasmoids can be migrated
safely, some other things may still require adapting as
setSource(QUrl::fromLocalFile(package.filePath("mainscript"))
must be changed to
setSource(package.fileUrl("mainScript"))