Extend tempo-bench to support sub-blocks

[klkvr]

Describe the feature

We want to have a way to send some of the tempo-bench transactions as part of subblocks.

With https://github.com/tempoxyz/tempo/pull/1205 we should now be able to identify which of the provided RPC urls are the actual validator nodes that can accept subblock transactions through sendRawTransaction.

Additional context

No response