When the export is in progress and the toast is shown, use the progress callback responses from the export to show the amount of documents exported in the toast.

Show a `Cancel` action on the toast while the export is in progress. This should open a confirmation modal: https://www.figma.com/file/4sXj42XyicBsdQkYIugHaV/Compass-Import%2FExport?node-id=1452%3A48466&t=FoEPTv8iHfB487DG-1 

If an error occurs, change the variant to danger and show the error in the toast: https://www.figma.com/file/4sXj42XyicBsdQkYIugHaV/Compass-Import%2FExport?node-id=1304%3A48403&t=FoEPTv8iHfB487DG-1 

On export success, update the variant and make the action `View file` which opens the file in the file browser.

Designs: https://www.figma.com/file/4sXj42XyicBsdQkYIugHaV/Compass-Import%2FExport?node-id=1019%3A45601&t=FoEPTv8iHfB487DG-1