Select/de-select all columns in Exporter column selection modal.

[ericclaeren]

When having a lot of columns in a resource export there's already the possibility to enable/disable the column by default in code See: https://filamentphp.com/docs/3.x/actions/prebuilt-actions/export#disabling-column-selection

It would be really nice if you could include a global option to de-select / select all columns for an import.
We have sometimes exports with 20+ columns where the user is only needing 3 columns and need to manually deselect the remaining 17 colums.