[Consensus] Make interaction among pacemaker and consensus modules asynchronous

[gokutheengineer]

Objective

Issue #395 explains necessity of separation of the consensus and pacemaker modules. We can identify two categories on how to do it:

1. Synchronously: Via calling functions of the consensus module from the pacemaker module. Since we shouldn't use reflect in the production code (except for testing), we need to expose necessary functions of the consensus module. PR [Consensus] Decoupling the Pacemaker and Consensus modules (Synchronous method) #427 follows this methodology.
2. Asynchronously: Using an event bus to define and send events from pacemaker module to consensus module. This methodology will be more idiomatic than what is implemented in PR [Consensus] Decoupling the Pacemaker and Consensus modules (Synchronous method) #427, since it exposes functions that are internal to the consensus module in shared module. We must seek a way to avoid doing this, and build asynchronous interaction.

Origin Document

I tried to implement asynchronous version first and faced the following problem:

The WIP I made on asynchronous implementation can be found in this branch: https://github.com/pokt-network/pocket/tree/issue/395-WIP-async-decouple-consensus-and-pacemaker-modules

Goals

• Asynchronous interaction between pacemaker and consensus modules

Deliverable

• Implement event bus, or use the existing one for interaction between pacemaker and consensus modules.

Non-goals / Non-deliverables

• Adding sleep statements
• Using reflect

General issue deliverables

• Update the appropriate CHANGELOG(s)
• Update any relevant local/global README(s)
• Update relevant source code tree explanations
• Add or update any relevant or supporting mermaid diagrams

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: @gokutheengineer
Co-owner: @Olshansk

[Olshansk]

LGTM, thanks for creating the ticket @gokutheengineer