Is your feature request related to a problem? Please describe.
We experience z-index issues in Kibana when using the data grid's full screen mode due to its use of fixed positioning. We work around this by applying global styles to reset the z-index values of other elements when the grid is in full screen mode (see elastic/kibana#178788). The issue is that in order to detect when the data grid is in full screen mode, we need to use mutation observers that check for the full screen class since the data grid doesn't offer another way to detect the full screen state.

Describe the solution you'd like
It would be much easier to implement our solution without workarounds if the data grid offered something like an onFullScreenChange(isFullScreen: boolean) callback that we could use to determine when our override styles should be applied.

Describe alternatives you've considered
The data grid could instead be updated to not use fixed positioning for full screen mode, but this seems like a larger and more difficult change on the EUI side.

Desired timeline
This isn't an urgent request since we have a workaround in place, but having it would help us remove some unpleasant tech debt.