[Consensus] Re-evaluate utility context management

[Olshansk]

Objective

Figure out how the utility context within consensus should be managed, refreshed and updated to avoid panics and race conditions.

Origin Document

This thread In #250:

Goals

• Avoid panics that can be a result of access to a nil utilityContext
• Avoid race conditions in the consensus lifecycle that can lead to issues in the use of utilityContext
• Update diagrams/documentation so it is abundantly clear how the consensus module should manage its instance of the utilityContext

Deliverable

• A PR updating how the utilityContext in the consensus module is managed
• Updated unit tests validating these changes
• Add/update the relevant sequence diagram if necessary mermaid
• Update documentation in the relevant READMes so this is clear
• Consider adding the following function per Gohkan's comment here: func (u *UtilityContext) GetPersistanceReadContext() { return u.Context.PersistenceRWContext.PersistanceReadContext }

Non-goals / Non-deliverables

• Change any interfaces in the ConsensusModule or UtilityModule

General issue deliverables

• Update the appropriate CHANGELOG
• Update any relevant READMEs (local and/or global)
• Update any relevant global documentation & references

Testing Methodology

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

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Creator: @Olshansk
Co-Owners: @andrewnguyen22

[Olshansk]

@andrewnguyen22 I want to discuss this in a protocol hour before someone takes it on.