[feature] W3ID: Create instance factory

# Description

As proposed in #12

It is required to implement a factory pattern which accepts a config and produces a class that includes methods and constructors for generation and management of W3IDs within an application's scope, i.e. given the context of the registry used, wallet keys used etc.

# Reference

n/a

# Acceptance Criteria

Implements the factory
Implements tests for the same