Port away from KDELibs4Support

Add explicit find_package() and #include's that are required and were
pulled in by KDELibs4Support.

krdb: remove one redundant #include, KColorUtils

kcm_fonts: send dbus message directly to org.kde.KDEPlatformTheme to
'refreshFonts'

kcm_style:
 - use KToolBar::emitToolbarStyleChanged() to notify of toolbar style changes

For the rest use the notifyKcmChange() private method to send the dbus
signal.

[1] https://invent.kde.org/frameworks/kdelibs4support/-/blob/master/src/kdeui/kglobalsettings.cpp#L860