fix(daemon): added poa block to isBlock check

[andreabadesso]

Motivation

PoA blocks are being stored with height = null in the Ekvlibro mainnet

Acceptance Criteria

• PoA blocks should be considered in the isBlock method so they get their height set.

Checklist

• If you are requesting a merge into master, confirm this code is production-ready and can be included in future releases as soon as it gets merged
• Make sure either the unit tests and/or the QA tests are capable of testing the new features
• Make sure you do not include new dependencies in the project unless strictly necessary and do not include dev-dependencies as production ones. More dependencies increase the possibility of one of them being hijacked and affecting us.