fix(rawdb): add hexutil.Bytes marshaling override for L1Origin.Signature

[jmadibekov]

Problem

#531 changed the signature's RPC API to use hex but missed updating the struct-level marshaling used by gencodec. That is, the the signature field was missing a JSON marshaling override, causing it to serialize as a number array (which is Go's default encoding) instead of a hex string.

This breaks Nethermind client, we discovered that from the tests failing in the NMC PR: NethermindEth/nethermind#10625. When L1Origin is embedded inside PayloadAttributes for engine_forkchoiceUpdatedV3, Nethermind returns "Invalid params" because it can't parse the number array format and expects the hex string by the Ethereum convention.

Changes

• Add Signature hexutil.Bytes to l1OriginMarshaling
• Regenerate generated files via go generate ./...

[davidtaikocha]

lgtm