Updating input for LinkedAnimationPanes [#46045405]

All the requisite data can be derived from the idea that this is a LinkedAnimationPane instead of a PredefinedGraphPane.

https://www.pivotaltracker.com/story/show/46045405
Supports LinkedAnimationPanes as vanilla GraphPanes

[#46045405] This is just a first step; inbound LinkedAnimationPanes are seen as valid but don't actually function differently from PredefinedGraphPanes (yet).
Generator properly outputs linkedAnimations

[#46045405] This makes the changes to push the linkedAnimation details through the generator from the creation of the LinkedAnimationPane to the runtime JSON output. Note that the "linkedAnimation" key is now in every AnimationTool as an empty array at minimum, and therefore it's added to an existing test case with an animation to reflect this change.

https://www.pivotaltracker.com/story/show/46045405
Compiled JS for 6081df752d8e0ed1e3142c1cc656c2c3a7161348