Generate an inventory of did:webvh resolver DIDs covering the MUSTs in the specification

[swcurran]

Create an inventory of the MUST statements in the [did:webvh spec] for which there should be a test case. Once that inventory is generated:

• consider if all the MUSTs are appropriate and adjust the spec accordingly.
• generate a list of DIDs that are to be created to test each remaining statement.

From there, we'll prioritize the DIDs to be created and published for resolver testing.