implement massive-migrations

[krlosMata]

NOTE

This PR in commonjs repository: https://github.com/hermeznetwork/commonjs/pull/41, should be merged first in order to fulfill test accordingly

PR

This PR implements the following:

• compute-acc-hash.circom
  • decode data-availability
  • computes accumulated hash chain
• hash-inputs.circom
  • computes input global hash
• migrate-main.circom
  • verify correctness of data-availability
  • decode transactions
  • check minimum batches or transactions to process
  • process migration transactions
  • process fee transaction
  • compute hash global inputs
• migrate-tx-states.circomto migrate
  • compute amount to migrate & fee to charge
  • selects sparse-merkle-tree processor functionality
  • computes new merkle tree index
• migrate-tx.circom
  • compute transaction states
  • build old and new states
  • sparse-merkle-tree processor to compute new root