javascript callback to get current selection of rows

[schlichtanders]

Hi there, it would be great if this could be the default TableView.jl for Pluto as well.

There it is great if one could access the selected rows (and columns) via Pluto's reactivity.
For this to work, just a javascript callback would be needed which is triggered everytime the selection changes.

[pfitzseb]

Should be doable for row selection, anything else is probably not possible with ag-grid community.