Type Indexing

[nitro-neal]

This proposal is to implement a new feature that can index and query dids by the registry type flag. This document will outline two potential approaches to implementing this feature, along with their respective pros and cons.
Approach 1: Implement Base ION/Sidetree Codebase and Create an Index Around Types
This approach involves integrating the new feature directly into the base ION codebase and creating an index centered on DID types.