ospfd: Implement non-broadcast support for point-to-multipoint networks

ospfd: Implement non-broadcast support for point-to-multipoint networks

This extends non-broadcast support to point-to-multipoint networks.
Neighbors will be explicitly configured and polled in lieu of multicast
dicovery. Toptotests and documentation updates are included.

Additionally, the ospf neighbor commands have been greatly simplified taking
advantage of DEFPY() capabilities.

The AllOSPFRouters (224.0.0.5) is still joined for non-broadcast networks
since it is joined for NBMA networks. It seems this could be removed but
it should done be in a separate commit.

Signed-off-by: Acee Lindem <acee@lindem.com>