fix: include base fee per gas for next block

[mattsse]

closes #7084

This fixes the bug by creating a fee entry to the best block at launch:

curl http://localhost:8545 -X POST -H "Content-Type: application/json" -d '{"id": 1, "jsonrpc": "2.0", "method": "eth_feeHistory", "params": ["0x5", "latest", [20,30]]}'

{"jsonrpc":"2.0","id":1,"result":{"baseFeePerGas":["0x3b9aca00","0x342770c0"],"gasUsedRatio":[0.0],"oldestBlock":"0x0","reward":[["0x0","0x0"]]}}

The baseFeePerGas has two entries because this is supposed to also include the next block's base fee which can be derived from the current block