add event Index to pool transactions

[alexcos20]

Changes proposed in this PR:

• add event index to pool transactions, so we can track multiple pool events in one tx

Query example:

query{
 poolTransactions{
  id,
  tx
  type
  eventIndex
}
}

Result:

{
  "data": {
    "poolTransactions": [
      {
        "id": "0x00128a5bbb7ca28de2f28ab78d6c4d2a3b8dfef1f1f9f65545a295903cec3e32-283",
        "tx": "0x00128a5bbb7ca28de2f28ab78d6c4d2a3b8dfef1f1f9f65545a295903cec3e32",
        "type": "EXIT",
        "eventIndex": "283"
      },
      {
        "id": "0x00128a5bbb7ca28de2f28ab78d6c4d2a3b8dfef1f1f9f65545a295903cec3e32-285",
        "tx": "0x00128a5bbb7ca28de2f28ab78d6c4d2a3b8dfef1f1f9f65545a295903cec3e32",
        "type": "EXIT",
        "eventIndex": "285"
      },
      {
        "id": "0x00128a5bbb7ca28de2f28ab78d6c4d2a3b8dfef1f1f9f65545a295903cec3e32-286",
        "tx": "0x00128a5bbb7ca28de2f28ab78d6c4d2a3b8dfef1f1f9f65545a295903cec3e32",
        "type": "SWAP",
        "eventIndex": "286"
      },
      {
        "id": "0x00128a5bbb7ca28de2f28ab78d6c4d2a3b8dfef1f1f9f65545a295903cec3e32-287",
        "tx": "0x00128a5bbb7ca28de2f28ab78d6c4d2a3b8dfef1f1f9f65545a295903cec3e32",
        "type": "SWAP",
        "eventIndex": "287"
      },
      {
        "id": "0x00128a5bbb7ca28de2f28ab78d6c4d2a3b8dfef1f1f9f65545a295903cec3e32-290",
        "tx": "0x00128a5bbb7ca28de2f28ab78d6c4d2a3b8dfef1f1f9f65545a295903cec3e32",
        "type": "SWAP",
        "eventIndex": "290"
      },
      {
        "id": "0x00128a5bbb7ca28de2f28ab78d6c4d2a3b8dfef1f1f9f65545a295903cec3e32-291",
        "tx": "0x00128a5bbb7ca28de2f28ab78d6c4d2a3b8dfef1f1f9f65545a295903cec3e32",
        "type": "SWAP",
        "eventIndex": "291"
      },
      ....
}

[jamiehewitt15]

Looks good to me