[Consensus][TECHDEBT] Consensus module techdebt consolidation

[Olshansk]

Objective

Consolidate, remove and tend to minor TODOs across the consensus module.

Origin Document

A lot of learnings and changes have been made to our process since the first implementation of the consensus module, so there is room to do some general 🧹 at a module-level perspective before we change or improve the business logic.

Goals

• Prepare the consensus module for a proper consensus <-> utility <-> persistence state hash computation
• Remove unneeded TODOs
• Consolidate repetitive TODOs

Deliverable

• A PR tending to the goals above only touching the consensus module (not pacemaker, persistence, utility etc...)
• A small sequence diagram showing cross-module context initialization

Non-goals / Non-deliverables

• Changing any business logic in the consensus module
• Changing cross-module interaction in the consensus module
• Changes tending to major TODOs across the module

General issue deliverables

• Update the appropriate CHANGELOG
• Update any relevant READMEs (local and/or global)
• Update any relevant global documentation & references
• Update the source code tree explanation
• Updated sequence diagram using mermaid for basic components

Testing Methodology

• All tests: make test_all
• LocalNet: verify a LocalNet is still functioning correctly by following the instructions at docs/development/README.md

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Creator: @Olshansk

[Olshansk]

The goal of this issue is to separate out the consensus-only changes from #237 into a smaller and readable PR.