Merge pull request #16450 from nabahr/static_joins

PIM: Implement static IGMP joins without an IGMP report

diff --cc doc/user/pim.rst
Simple merge

diff --cc pimd/pim_cmd.c
Simple merge

diff --cc pimd/pim_iface.c
Simple merge

diff --cc pimd/pim_memory.c
Simple merge

diff --cc pimd/pim_memory.h
Simple merge

diff --cc pimd/pim_nb.c
Simple merge

diff --cc pimd/pim_nb.h
Simple merge

diff --cc pimd/pim_nb_config.c
Simple merge