fix(contracts + proposer): checkpoint block hash

[ratankaliani]

Overview

• Move back to the original L2OutputOracle initializer pattern to reduce the diff. Remove the owner role, which is covered by the owner of the proxy.
• Remove the chainId from the initialization parameters, as the rollupConfigHash includes the chainId.
• Fix checkpointBlockHash to handle non-zero block hashes only: This fix ensures that only non-zero block hashes are stored, preventing a potential attack. The attack allowed users to set the blockHash for blocks older than 256 blocks to bytes32(0), which could block proofs that took over one hour to generate from being submitted on-chain. Generating proofs typically takes much less than an hour, so in practice this would have been difficult to exploit.
• Simplify checkpointBlockHash and proposeL2Output functions to accept only the l1BlockNumber, as passing l1BlockHash is redundant in this context.

Additional Context

Note: This PR has a breaking change to the binaries, so we'll need to re-compile them along with the contract changes.
Note: This PR also has a breaking change to the contract, so we'll need to re-deploy, rather than upgrading.