[Core] Create design document for save points and rollbacks

[jessicadaugherty]

Objective

Uncover the various implementation points throughout the codebase where save points and rollbacks should be implemented.

Origin Document

While some implementation points have been identified here and a ticket to rollback to them has been defined here, they should be fully mapped out to understand the extent of the effort of save points and rollbacks and to create smaller issues.

Goals

• Identify all of the implementation points for save points and rollbacks in a design doc and create relevant issues for future development

Deliverable

• Create a save points and rollbacks design document (bonus: mermaid diagrams)
• Create issues for implementing save points and rollbacks (rescope [Persistence][Core][Savepoints/Rollbacks] Implement KISS SavePoints - Serialize WorldState from Persistence #327 and [Persistence][Core][Savepoints/Rollbacks] Implement KISS Rollbacks - Deserialize WorldState to Persistence #435)
• (If applicable) Document areas of further investigation

Non-goals / Non-deliverables

• Implementing the save points or rollbacks

General issue deliverables

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

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: @jessicadaugherty
Co-owner: @Olshansk