Trigger header element animation when moving screens from header

Nobody has claimed this yet.

The issue right now is that any object that have a shared element must be in the same stack and appear between screen transitions. If you want to do fancier animation with objects from outside the stack, like headers (headerLeft, headerRight), it doesn't fire the functions needed to do this.

For example you have a profile picture in the header of the stack and when tapping on it, the profile pic resized to fit into a "User settings" screen. And if you press the back button the profile picture gest smaller and is in the header again.

Is it something that could be implemented somehow? A different library [FluidTransitions](https://github.com/fram-x/FluidTransitions) had the option to implement something like this.

No files, tests, or entry points are named. Start by tracing how shared-element transitions are handled for React Navigation headers, especially headerLeft and headerRight, and compare the referenced FluidTransitions behavior; done means header elements animate into and out of screens during forward and back navigation.

Written by the indexing model from the issue text.