chore(Modularization): Revisit current project modules

[lukas8219]

• Redesign router package into composable submodules.
  • Create peer_discovery package
    • Responsible for keeping the possible upstreams up to date.
    • Current one's DNS SVR record based, Kubernetes Watch based
  • Create transports package
    • Reusable interface that we can enable N transports, i.e communication with upstreams
    • Currently only HTTP-based
• Review current current logger implementation
• Create reusable ConnectionTracker to be reused between LoadBalancer and SideCar