Modularise QBFT

[jframe]

Make the QBFT less dependent on other Besu modules so it can be reused as a library. The initial use case is to reuse QBFT as a library in a QBFT CL implementation.

** Acceptance Criteria **

• Separate QBFT core including state machine that is agnostic of networking and types from the Besu-specific implementation
• Allow for any block type to be used in QBFT
• Allow networking to be changed
• Remove block creation from QBFT and into Besu QBFT module

[pullurib]

@jframe , I spent some time working on QBFT issues and got a good understanding of algo , code and flow . Let me know if I can help with this in any way.