Regression: flyTo no longer works in react-leaflet@3+

[louh]

Here's an example of flyTo in action on react-leaflet@2.x:

Screen.Recording.2023-03-05.at.2.20.52.PM.mov

• When panning somewhere outside the current viewport, there is a smooth animation (the animation is faster than map tiles can load, but it's still happening) to center the new location inside the viewport.
• When clicking inside the current viewport, there is a smooth animation to center the clicked location in the viewport.

In react-leaflet@3+ (including @4) flyTo functionality appears to have been removed:

Screen.Recording.2023-03-05.at.2.22.08.PM.mov

• When panning somewhere outside the current viewport, the viewport relocates only the minimum necessary to allow the popup to appear in the viewport.
• When clicking in the current viewport, the viewport pans on the minimum distance necessary to allow the popup to appear in the viewport.
• If clicking in the current viewport and the popup is already fully contained inside the viewport, no panning occurs.

This is not a critical breaking bug, but the effect is nice to have, particularly since the popup may be located in an awkward spot.