this ports most of libplasma away from sycoca, using instead
a combination of KPluginLoader and KPackage::PackageLoader instead
(so eventually using their own little caches instead of the
global sycoca cache)
a kservicetypetrader call is left in the loading of
containmentactions since is the only way to make an older
workspace still work, but is only a fallback, so containmentactions
in plasma-workspace can be ported eventually as well
Change-Id: Ie9579c3e01284f6d97043e22d01bbe63d3c3f45a
REVIEW:123626
ea924b1469