- Add tests connecting TxSelector, BatchBuilder, ZKInputs, ProofServer
- Added test to check that the signatures of the PoolL2Txs from the L2DB
pool can be verified, to check that the parameters of the PoolL2Tx match
the original parameters signed before inserting them into the L2DB

- Remove MaxL1CoordTxs parameter from the TxSelector because this parameter
  doesn't exist
- Use ChainID in l1tx byte encoding
- Pass txprocessor configuration to batch builder via an existing parameter

- Abstract TxProcessor from StateDB
- Upgrade to last version of go-merkletree for the key-value DB usage

Introduce a constructor parameter for the StateDB called `keep`, which tells
how many checkpoints to keep.  When doing a new checkpoint, if the number of
existing checkpoints exeeds `keep`, the oldest ones will be deleted.

- Update IntermediateState FinalAccFee values to fit in the Circom circuit expected inputs
- Add ZKInputs generation test with transactions generated by Til
(TestZKInputs6)
- BatchBuilder: remove redundant MakeCheckpoint call

Add HashGlobalInputs for ZKInputs compatible with js & circom circuits version.

Compatible with hermeznetwork/commonjs at version: c6a1448db5
(c6a1448db5)

- Implement new TxID spec that distinguishes L1UserTx and L1CoordinatorTx
- Replace some type []*Foo by []Foo
- Fix HistoryDB & L2DB bug: in case of error, a rollback was applied and the returned error was nil
- Reorder inserts in historydb.NewHistoryDB() to follow foreign key dependencies
- Add initial synchronizer test with test.Client (for now, only tested l1UserTxs, blocks, addToken)
- Update L1UserTx event in test.Client

Add StateDB compute nonces on ProcessTx L2Tx, and update StateDB for
type TypeSynchronizer, TypeTxSelector, TypeBatchBuilder

Add Coordinator goroutines & channels processes
- Add Coordinator goroutines & channels
- Add Coordinator test to debug batches
- Add MakeCheckpoint call after BatchBuilder BuildBatch process
- Update ethClient BlockByNumber to return hermez/common.Block instead of go-ethereum/core/types.Block

- Update GHA lint.yml increasing timeout time to avoid GHA Lint errors
- Update common.BatchNum & common.Idx & common.Nonce usage in StateDB
- Add abstraction method of processTxs to StateDB
    - Which will be used by Synchronizer & BatchBuilder

Migrate TxProcessors from BatchBuilder to StateDB in order to be used by
BatchBuilder & Synchronizer