Monitor limbo tx pool

[zjg555543]

On the mainnet, we should add the monitor for limbo txs. As we will set zkevm.limbo: true for sequencer.

curl --location 'http://127.0.0.1:8123/' \
--header 'Content-Type: application/json' \
--data '{
    "id": 1,
    "jsonrpc": "2.0",
    "method": "txpool_limbo",
    "params": []
}'