Adding `chainName` parameter to `get_avl_head` request

[jordibonet-lambdaclass]

According to RPC Queries from VectorX, the chainName parameter is required when querying.

Testing

Using the following configuration:

AVAIL_CHAIN_NAME=turing
CONTRACT_CHAIN_ID=11155111
VECTORX_CONTRACT_ADDRESS=0xe542db219a7e2b29c7aeaeace242c9a2cd528f96

Run this command:

curl http://localhost:8080/avl/head | jq

Expected output:

 % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    38  100    38    0     0     78      0 --:--:-- --:--:-- --:--:--    78
{
  "data": {
    "end": 263160,
    "start": 149761
  }
}