[libkwineffects] Replace property name lookup with calling the virtual methods
EffectWindow proxies its properties from the client/deleted's
QObject::property(char*) is a slow string search. It's a loop
of string comparisons not a hash lookup!
QML's use of properties is different, there's a property cache.
It's fetched multiple times for every window in every paint of some
effects (such as blur). Hotspot shows this as a significant amount of
the render pass (X11) with nothing in kwin animating.
This patch replaces the macro that does
with a macro calling the relevant function directly without metaobjects.
This also improves type safety for future changes.
Existing unit tests
Ran it for a bit
Reviewers: KWin, graesslin
Subscribers: graesslin, zzag, broulik, kwin
Differential Revision: https://phabricator.kde.org/D16602