CFM process flooding to interfaces based on mesh groups

A mesh group is a set of interfaces with similar flooding behavior, commonly used in the configuration of LDP BGP VPLS interworking. The flooding behavior configured for each mesh group is used by all the interfaces in that mesh group. The Connectivity Fault Management Protocol uses the data path semantics for packet flooding and therefore must adhere to the flooding behavior for mesh groups. The connectivity-fault management process (cfmd) can now support VPLS and virtual-switch routing instances.