[EuiTablePagination] Update pagination with context menu that announces selected row count

[1Copenut]

I filed an improvement ticket for EuiContextMenu to announce single selected items ( #6648 ). I'd like to update the data grid pagination with this improvement when it's finished.

[cee-chen]

I don't think this needs to be a separate issue; if we update the underlying EuiContextMenu all pagination components should automatically inherit.

[cee-chen]

After re-reviewing, this should be handled in the EuiTablePagination component rather than in data grid. That way basic and in memory tables also receive this a11y improvement

[1Copenut]

I started on this update late Friday afternoon. It's remarkably similar to the work I PR'ed in #7153.