Add a fluent animation for pane zooming

[zadjii-msft]

Related to #1001, and a follow-up to #6989

It'd also be nice if we had an animation. Idk if you want that to be a part of #1001 though. If you do punt on the animation, could you just add a note on that issue (or open a new one).

[zadjii-msft]

Alright so insomnia-thought:

• When we zoom the pane, don't remote the other panes from the tree. Instead, take the zoomed pane's control out.
• add the zoomed pane's content to the root grid of the page.
• resize the TermControl to be the full size
• force the panes control to start as a size of W,H=(originalWidth, originalHeight).
• force the panes's control (the one that's now a child of the root grid) to be at the same x,y it was originally (set a Translation maybe?)
• Animate the pane's control's x,y -> (0,0)
• Animate the pane's w,h -> (rootWidth, rootHeight)

so the pane will just be drawn on top of the other panes in the tree, and it'll look like it started where it originally was, and at it's original size, but it's actually just on top of all of them.

---

We'd want to have another new animation for "move focus while zoomed", once #7215 is done too, but one step at a time