Sequencer adds system transactions to blocks as regular transactions

[eyusufatik]

Should be done right after #1791 .

TODOs:

• Whenever the sequencer would normally change the underlying L1 block by using a different l1_hash and l1_height in its soft confirmations, it will now add a SystemEvent::BitcoinLightClientSetBlockInfo evm tx from the system signer to the L2 block.
• Whenever it needs to add deposit_data to the soft confirmation, now it will crate a SystemEvent::BridgeDeposit evm tx and add it to the L2 block.