feat(derive): BatchValidator stage

[clabby]

Overview

Before we can make the BatchProvider multiplexing stage described in #699, we need to make the new batch stage to replace the BatchQueue.

This stage should:

1. Only accept SingleBatches.
   • Validate the SingleBatches with the L1 origins within the stage.
2. Keep track of the L1 origins of the unsafe chain, and prune them appropriately, identical to the BatchQueue
3. Handle empty-block derivation on sequencer window expiry, once the previous stage has reached Eof.