op-node: batch-decoder: Fjord Frame Timestamp fix

[pcw109550]

Description

Two fixes;

• derive.BatchReader got aware of channel's timestamp(or frame's timestamp) starting from Fjord network upgrade. Batch decoder manually reconstructs frames from json, and previously it did not supply frame timestamps because it was not necessary for pre-Fjord. Now we need the correct timestamp.
• Fixed json key typo for compression algos, for channels.

Tests

Manually tested at the first Fjord op-mainnet batch.

First fetch batch transaction.

./batch_decoder fetch --start=20277208 --end=20278210 --sender=0x6887246668a3b87F54DeB3b94Ba47a6f63F32985  --inbox=0xFF00000000000000000000000000000000000010 --l1=[L1_RPC] --l1.beacon=[L1_BEACON]

Then reassemble to make a channel.

./batch_decoder reassemble --inbox=0xFF00000000000000000000000000000000000010 --in=/tmp/batch_decoder/transactions_cache

Before this patch, batch decoder emitted Err: cannot accept brotli compressed batch before Fjord error, and stores channels which contains no batches. After this patch, It correctly stores batches and compression algos.