Run Stateless Validation code as part of mainnet

[pugachAG]

In the initial implementation of Stateless Validation we do not change the way we create blocks/chunks. It means that if we were to run Stateless Validation code as part of the current mainnet, it would produce exactly the same blocks. This can be used to check some of the Stateless Validation functionality on mainnet traffic.

We can do the following with running RPC node with Stateless Validation code as part of mainnet:

• Produce state witness for each chunk and monitor its size.
• Self-validate the chunk using state witness. This way we ensure correctness of state witness production and chunk validation.
• Simulate stateless validation with single validator:
  • Use RPC node that tracks all shards to produce state witness.
  • Use separate RPC node that doesn't track any shard as stateless validator.
  • The first node sends validation requests to second one and awaits the endorsements. This way we can check end-to-end validation latency including the network. Also we ensure that we don't accidentally use State in chunk validation code.