Proxy handle invalid cert for OP

[bxue-l2]

See original issue posted here. Layr-Labs/hokulea#25 (comment)

When an op-batcher posts an invalid cert, the proxy currently returns a 400, or 500 error, see https://github.com/Layr-Labs/eigenda-proxy/blob/main/server/handlers.go#L106

On the op-node side, it would get stuck. Copied two possible solution from the issue above

Two solutions:

1. proxy returns an empty byte, not reporting an error. As such, the the frame_queue in the derivation pipeline will filter out the empty byte
2. proxy returns a special error code, such that the op-node daclient knows to discard the data

Currently as far as I understand, the error flow like below

1. https://github.com/ethereum-optimism/optimism/blob/develop/op-node/rollup/derive/l1_retrieval.go#L63
2. https://github.com/ethereum-optimism/optimism/blob/develop/op-alt-da/daclient.go#L53
3. https://github.com/ethereum-optimism/optimism/blob/develop/op-node/rollup/derive/altda_data_source.go#L93

I have gone deep when it got to 3, but from the comment it will continue to retry that cert, and essentially deadlock the system