add tests forceExit, forceTransfer, transfer & exit with amount = 0

[krlosMata]

This PR does the following:

• updates npm package @hermeznetwork/commonjs to version 0.3.2
  • check fixes here
• add test for the following cases:
  • L1 forceExit with amount = 0
  • Two L1 forceExits: amount != 0 & amount = 0
  • L1 force Transfer with amount = 0
  • Two L1 forceTransfers: amount != 0 & amount = 0
  • L2 exit with amount = 0
  • Two L2 exits: amount != 0 & amount = 0
  • L2 transfer with amount = 0
  • Two L2 transfers: amount != 0 & amount = 0