PoolL2Tx.Info contains information about the status & State of the
transaction. As for example, if the Tx has not been selected in the last
batch due not enough Balance at the Sender account, this reason would
appear at this parameter.
This will help the client (wallet, batchexplorer, etc) to reason why a
L2Tx is not selected in the forged batches.

L2Tx.TokenID is not on the data obtained by the Synchronizer from the
blockchain, but is set by the TxProcessor when processing the
transactions in the StateDB.

Test TxProcessor zkInputs against a real proof server

- Til
  - update Til users BJJ key generation for better js tests
    compatibility
- Common
  - PoolL2Tx to L2Tx use AuxToIdx in case that ToIdx is 0
  - Update ZKInputs parameter descriptions
- TxProcessor
  - Fix AccumulatedFees in case that there is no CoordIdx for that token
  - Fix zki.NewExit usage
  - Use same order for AccumulatedFees & FeeIdx & FeePlanTokens
  - Add Nonce usage to ExitLeafs
  - Update TestZKInput6 and check its compatibility with circom Hermez
circuits

- Til
  - tests that were using `til.SetBlockchainMinimumFlow0` have been
updated, as now the L1CoordinatorTxs are placed simulating TxSelector
creation (when needed, not before)
  - Add `EthSk` to `tc.User` to allow to sign `AccoutCreationAuths` at
the tests flows
- TxProcessor
  - for L2Txs get TokenID from tx.FromIdx Account.TokenID instead than
  - update tests vectors for new values
from tx.TokenID (which not always is set)
- Common
  - move TxIDsFromL2Txs & TxIDsFromPoolL2Txs from `coordinator` to
`common` to allow usage from other packages

Update usage of `*babyjub.PublicKey` to `babyjub.PublicKeyComp`
- when the key is not defined, internally is used `babyjub.EmptyBJJComp`, which is a `[32]byte` of zeroes of type `babyjub.PublicKeyComp`
- the API continues returning `nil` when the key is not defined

For each tx, move the logic of setting the Type and TxID to separate functions,
so that they can be called when necessary.

In synchronizer, set all the required fields using the `SetID` and `SetType`
for l2txs when needed.  This is necessary because the `ProcessTxs()` works with
`common.PoolL2Tx`, which misses some fields from `common.L2Tx`, and because
`ProcessTxs()` needs the Type to be set, but at the same time `ProcessTxs()`
sets the Nonce, which is required for the `TxID`.

- Add SignatureConstant to L1Tx.TxCompressedData
- ZKInputs generation works initial version working and compatible with circom Hermez circuit
    - Lots of small updates for circuits compatibility
- Update version (with new changes) of `go-iden3-crypto` & `go-merkletree`

- Add L1Tx TxCompressedData method
- Add PoolL2Tx TxCompressedDataV2 method
- Update ProcessTxs logic
- Add ZKInputs Intermediate States & Fee parameters calculation

- Add TxSel Nonce sort
- Fix surplus from refactors
- StateDB reuse computation of ToIdx across Synchronizer, TxSelector,
BatchBuilder

Add transakcio set type definition, add set loading, move transakcio to
package, adapt branch to last master updates (fix compile due new common
types & git conflicts).
Update tests to pass the test, pending to adapt to new Transakcio
interface.

- 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

* WIP: rebase

* Make nullable fields use pointers

Add TxID calculation & New{Layer}Tx Type

New{Layer}Tx methods that compute the `TxID` & `TxType` values from the
transaction values:
- NewL1Tx
- NewL2Tx
- NewPoolL2Tx

Add TxID Scanner & Valuer for database/sql

HistoryDB & L2DB & API packages tests will need to be addapted to the
TestTransaction generation once is done.

* WIP rebase

* Combine both SQL DBs

* API and DB refactor

Change endianness to BigEndian (ಥ﹏ಥ), spec has been updated to achieve
compatibility with js & smart contracts & circuits implementations.

- gofmt - Gofmt checks whether code was gofmt-ed. By default this tool runs
  with -s option to check for code simplification
- goimports - Goimports does everything that gofmt does. Additionally it checks
  unused imports
- golint - Golint differs from gofmt. Gofmt reformats Go source code, whereas
  golint prints out style mistakes
    - checks the uncommented exported functions & types

Update the code to fix the lint checks.

Add linter checks to GHA & Fix code to pass lints.
The linters added are:
- whitespace: Tool for detection of leading and trailing whitespace
- gosec: Inspects source code for security problems
- gci: Gci control golang package import order and make it always deterministic
- misspell: Finds commonly misspelled English words in comments
- gomnd: An analyzer to detect magic numbers

The file utils/utils.go is excluded from the checks of gomnd, as uses magic numbers through the code

- 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

Implements the hash to be signed from PoolL2Tx, compatible with javascript version.
Implements the signature verification for a given PoolL2Tx.