[fw] broadcast/replicast forwarding strategy + best-route override

[r2dev2]

• fixes bug in bestroute forwarding ER tagging where ER was out of sync with nexthop after sort
• refactors strategy interface to take in a list of tuple of nexthop/ER
• override to setting the strategy to best-route when ER tag is detected (see slide 16) - behavior might be reconsidered in future, but keep for now
• implements broadcast forwarding strategy to forward interest packet to all next hops
• implements replicast forwarding strategy (n interest packets sent to n unique egress routers)
• changes router to use broadcast forwarding in its advertisement interests and for localhop advertisement svs

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TODO before ready for review:

• test replicast using an svs application in e2e env (NOT the ndnd advertisement svs as that is localhop)