Qbft block type

[jframe]

PR description

Adds a specific QBFT block type, decoupling this type from the Ethereum block so that QBFT can be used for other blocks e.g. Could be used for a beacon block on a L2.

This PR still uses the Ethereum block header a follow on PR will change this to keep this PR smaller.

Changes

• Introduced a qbft block type replacing the Ethereum block type. Note the Ethereum block header is still being used for now.
• Created services/type interfaces in qbft core for operations that need to be performed on the block by qbft such as validation, encoding, importing, creating etc.
• Added adaptors to the main qbft module to allow the use of Besu classes and services as qbft core types for use in the qbft core module

Fixed Issue(s)

Thanks for sending a pull request! Have you done the following?

• Checked out our contribution guidelines?
• Considered documentation and added the doc-change-required label to this PR if updates are required.
• Considered the changelog and included an update if required.
• For database changes (e.g. KeyValueSegmentIdentifier) considered compatibility and performed forwards and backwards compatibility tests

Locally, you can run these tests to catch failures early:

• unit tests: ./gradlew build
• acceptance tests: ./gradlew acceptanceTest
• integration tests: ./gradlew integrationTest
• reference tests: ./gradlew ethereum:referenceTests:referenceTests

[usmansaleem]

LGTM - very minor nitpick which can be ignored.