selftests: net: bridge: add vlan mcast_querier_interval tests

Add tests which change the new per-vlan mcast_querier_interval and
verify that it is taken into account when an outside querier is present.

TEST: Vlan mcast_querier_interval global option default value       [ OK ]
TEST: Vlan 10 mcast_querier_interval option changed to 100          [ OK ]
TEST: Vlan 10 mcast_querier_interval expire after outside query     [ OK ]

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