selftests: net: bridge: add test for igmpv3 exc -> is_exclude report

The test checks for the following case:
     state          report        result                  action
   EXCLUDE (X,Y)  IS_EX (A)     EXCLUDE (A-Y,Y*A)        (A-X-Y)=GMI
                                                         Delete (X-A)
                                                         Delete (Y-A)
                                                         Group Timer=GMI

Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>