animation: add BezierCurve, AnimationManager and AnimatedVariable

[PaideiaDilemma]

Moved from Hyprland.

I simplified the AnimationManager a bit, so that it only stores references to active variables. (Previously registerVar and unregister existed as well)

I also changed the way variables are removed from active, so that we don't have to search through the active vector each time an animation ends. It now just replaces the whole vector with a new one containing all variables that return true for isBeeingAnimated() on a call to tickDone. disconnectFromActive is only used for the dtor of CBaseAnimatedVariable.

CBaseAnimatedVariable stores a reference to the animation manager for now in order to connect/disconnect an active var to the animation manager. (discussed that with vaxry)

CGenericAnimatedVariable is only defined in the header and takes two template parameters. The type of the underlying value and a context. The context is there to store damage policy and variable parent (window,workspace,layer) in Hyprland and the parent widget in hyprlock.

The test shows an example usage of AnimationManager and AnimatedVariables.

[PaideiaDilemma]

Now uses smart pointers for throughout.

[vaxerski]

generally looks nice

[vaxerski]

rest approved

[vaxerski]

thank you!