[RFC] Cluster mode architecture

[a-wing]

• live777-gate is stateless
• All state storage in redis
• live777-core and live777-gate, live777-core as server, live777-gate as client loop live777-core (look like prometheus)
• P2P mode is live777-core in edge, live777-gate forward signaling
• live777-core and live777-core be able re-whip stream