[effects/slidingpopups] Port to TimeLine

Summary:
In addition to porting to TimeLine, this change also fixes quadratic
scaling of animation durations:

animData.fadeInDuration = animationTime(mFadeInTime);
animData.fadeOutDuration = animationTime(mFadeOutTime);

where

mFadeInTime = animationTime(...);
mFadeOutTime = animationTime(...);

Depends on D13740

Test Plan: Opened/closed Kickoff.

Reviewers: KWin, mart

Reviewed By: KWin, mart

Subscribers: kwin

Tags: KWin

Differential Revision: https://phabricator.kde.org/D13801