M5: Implement chain sync algorithm for syncing peer state

[creativcoder]

Issue summary

On node startup, it will run into two phases depending on the state:

1. Bootstrapping: The node doesn't have any past state or is a new node.
2. Catchup: The node has a past history of state and is trying to sync to the latest state from discovered peers.

During the above phases the node will also have to validate the blocks and discard or accept them.

The goal is to implement the functionality for downloading the blocks, validate and trigger chain selection during forks.

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