[Test] Integration test cases

[frisitano]

Overview

To increase confidence in the rollup-node, we should implement the following test cases. Note that this list is not exhaustive and should be expanded on:

• Batches received from L1 should correctly update the L2 safe block head.
• Batches that have been finalized on L1 should update the L2 finalized block head.
• L1 reorg that invalidates a batch should result in the safe head reverting to the latest L2 block associated with the previous batch.
• L1 reorg that invalidates an L1 message which has been included in a block should result in an L2 reorg.
• Invalid block that is gossiped over the network should be rejected and the peer should be penalized.
• Block with invalid signature that is gossiped over the network should be rejected and the peer should be penalized.