Also, replace usage of time.Duration by time.NewTimer, because the later allows
replacing timers by stopping them before so that we never leak resources.

- In test, doing the `net.Listen` outside of the goroutine guarantees that we
  are listening, so we avoid a possible datarace consisting of doing an http
  request before listening.
- In packages that run an http server: doing the listen first allows
    - Checking for errors when opening the address for listening before
      starting the goroutine, so that if there's an error on listen we can
      terminate grafecully
    - Logging that we are listening when we are really listening, and not
      before.

Previously the coordinator was erroneously using Slot.BatchesLen to determine
when anyone can forge.  The correct behaviour is implmenented with the boolean
flag `ForgerCommitment`, that is set to true only when there's a batch before
the deadline within a slot.

Delete Slot.BatchesLen, and the synchronization code of this value from the
Synchronizer, as this is not needed

- Implement Pipeline.prepareForgeBatchArgs()
- Add a minimal stress test for the coordinator (that also runs the
  synchronizer)
- Update txprocessor.ProcessTxs() to return valid results for batches without
  transactions
  	- Add the boilerplate for the corresponding test, leaving as TODO the
	  zkInput values
- Update prover client to use the same point format as proof server (projective)
- Update interface of TxSelector.GetCoordIdxs to also return the authorizations
  to create accounts that go with the l1CoordinatorTxs.