feat: adding cli --rpc.txfeecap flag

[rrrengineer]

Working on #15618

[mattsse]

cool, great start, some suggestions

[rrrengineer]

Implementation tested with op-reth full node

• no flag, default value 1 ETH
• --rpc.txfeecap=0, no cap on tx fee

{
    "jsonrpc": "2.0",
    "id": "1",
    "error": {
        "code": -32603,
        "message": "tx fee (1.11 ether) exceeds the configured cap (1.00 ether)"
    }
}

[mattsse]

cool, love the tests, more pedantic unit nits

and a question regarding the actual check

[rrrengineer]

@mattsse Please take a look at the changes and let me know if more adjustments are needed.

[mattsse]

ty,

more nits

[mattsse]

lgtm!

ty