feature request: toggles for sharing y-axis limits across viewers

[bmorris3]

The plugins make it easy to have a view of your data split between a time and phase viewer.

Since the x-axis is different we wouldn't want those limits to be shared, but there are times when you may want your y-limits shared across viewers. I'm not sure where to put a button for this, but I'd love a toggle for e.g. "sync y-limits" somewhere.

[kecnry]

would you want this across all viewers or a custom subset of viewers? If it's across all viewers, we can easily share the infrastructure proposed in spacetelescope/jdaviz#2219 for have a "matched" pan-zoom in just the y-direction.