packaging: setup: allow interactive NFS exports cleanup

allow interactive NFS exports cleanup with engine-cleanup-2

- Refactored uninstall for allowing file grouping
- Added group for exportfs files
- Cleanup optional uninstall groups like exportfs only if requested.

Change-Id: I16b5920f0cfc9f564aa92f7e0d5a6d33af5e0b44
Signed-off-by: Sandro Bonazzola <sbonazzo@redhat.com>