* ci: better solc warnings check

Use `forge build --force` to force a build so that the warning check can
be observed. CI should fail on this commit

* contracts-bedrock: fix warnings

Fix the failed solc build

See the failed workflow here:
https://app.circleci.com/pipelines/github/ethereum-optimism/optimism/59631/workflows/b93bc600-e772-4ba9-98ed-a0b6f48683c7/jobs/2512271

* foundry: add ignored error code