[P2P] Pre2P RainTree

[Olshansk]

Objective

Implement the RainTree algorithm described here on top of the Pre2P module.

Origina Document

This issue was created after the work in #80 was mostly complete but created for completeness.

Goals

Deliverables

• Implementaiton
• Tests
• Documentaiton

[Optional] Testing Methodology

• Add new unit tests
• Create a new test suite for running RainTree tests (similar to HotPOKT)
• Verify that everything works on the 4 node LocalNet framework described here

Non-goals

• Migrate Pre2P to P2P (to be done in a different issue)
• Implement all the components of a fully functional P2P layer (peer discovery, redundancy, complete configs, async IO, etc...)

Creator: @Olshansk
Co-Owners: @andrewnguyen22 @derrandz