[libkwineffects] Use Q_DISABLE_COPY in AnimationEffect

Summary:
AnimationEffect is an identity so delete copy constructor and copy
assignment operator.

Test Plan: Compiles.

Reviewers: #kwin, davidedmundson

Reviewed By: #kwin, davidedmundson

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D17838