Add a frequency slider for cyclic graphs

When we set an animation to be cyclic, in the animation graph editor, the key frames are fit to a curve and set to be repeated with the "Cycles" graph modifier.

This is great for when we want a specific animation to continue, over and over again, at the same rate. In the modifier itself, we even have some advanced features like setting start and end frames for the repeat, and bleed-in and bleed-out times.

What we unfortunately do not have, which would be critical to accomplishing a lot of animations without having to do them all by hand, is control over the relative rate of these cycles at a specific time.

As an example of use, perhaps something is happening faster, like an accelerating bicycle, and we want the wheel cycling to repeat four times as quickly at the end of our animation as at the beginning. Maybe we're animating a jogger, and want our inhaling and exhaling animations to pick up speed at a certain point in the timeline when they're most exerted. At the moment, that isn't easy to do.

If we had a wavelength or frequency control on this modifier, especially if it could be driven by a driver or keyframes, the task would be trivial!