[DRAFT] feat: Add Escrow Milestones Transaction Type

[wtfsayo]

Description

Motivation & context

Code review

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• I have done a self-review of my own code
• Any new and existing tests pass locally with my changes
• My changes generate no new warnings (lint warnings, console warnings, etc)