Split and merge #465 to master

[ChihChengLiang]

What is wrong?

As #465 getting fat and the exploration is nearly maximized, it's time to split it to smaller PRs and merge them back to master.

How can it be fixed

• Update a state machine class and a chain class for the testnet. Add testnet chain and Xiao Long Bao state machine #489
• Add Slot ticker Fix #437, add slot ticker #490
• Add validator service Validator service based on beacon plugin #525
• Add validator service and slot ticker to the beacon plugin. Gather validator with beacon node plugin #594
• Update sync and the receiving server. Add receive server for validator service #580
• Add integration tests for two trinity-beacon clients initiating and syncing Gather validator with beacon node plugin #594
• The network setup experience The network setup user experience #516