Remove digiKam kio-slave dependencies with digikamcore shared library.

By this commit, we limit external shared lib influence to kio-slave. For ex, why we need to link kio-slave with
Marble shared lib which is linked to digikamcore and can break binary compatibility when user update external packages.
This commit link digiKam kio-slave only with digikamdatabase. This will limit shared libs to load at kio-slave start, which
can be faster and prevent time-out under MACOSX and Windows.
CCBUGS: 294835
CCBUGS: 224038