RSP-1503: Disable empty selection for single selection mode (#225)
* RSP-1503: Disable empty selection for single selection mode
* RSP-1503: add prop to singleSelection
* RSP-1503: adding tests
* RSP-1503: lint fix
* RSP-1503: switch to allowsEmptySelection api
* RSP-1503: remove interface
* RSP-1503: remove extra interface
* RSP-1503: rename to disallowEmptySelection
* RSP-1503: lint error
Co-authored-by: Daniel Lu <dlu@livefyre.com>
Co-authored-by: Robert Snow <rsnow@adobe.com>