selftests: net: bridge: add tests for igmpv3 is_include and inc -> allow reports

First we test is_include/include mode then we build on that with allow
effectively achieving:
  state          report        result                 action
 INCLUDE (A)    ALLOW (B)    INCLUDE (A+B)           (B)=GMI

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