Complete implementation of DID URL Dereferencing and ensure it passes test suites

[frankhinek]

A partial implementation of DID URL Dereferencing was added to @web5/dids and is currently being used in @web5/credentials.

Assuming we want to continue / expand use of DID URL dereferencing the current implementation primarily supports returning the entire DID document or Dereferencing the Secondary Resource.

Full support for Dereferencing the Primary Resource should probably be added.

The W3C Test Suites could be used to validate our implementation.

References:

• DID Core Specification, § DID URL Dereferencing
• DID Resolution Draft Community Group Report, § Dereferencing a DID URL
• DID Resolution Draft Community Group Report, § DID Dereferencing Result
• W3C Test Suite, did-url-dereferencing