Fix urlFromDid() logic to correctly handle path segments

[zscott]

Wrote a few tests and implemented logic to support optional paths according to Web DID Method Specification.

Previously the urlFromDid() logic supported:
did:web:domain/path/subpath -> https://domain/path/subpath

This is an invalid DID.

With this PR urlFromDid() supports:
did:web:domain:path:subpath -> https://domain/path/subpath/did.json

[dmitrizagidulin]

@zscott thank you so much for the PR.
In case you're curious why it was handling / path segments before -- I think I was front-running the discussion on issue w3c-ccg/did-method-web#52 (I expected the spec to go in the direction where did:web:domain/path/subpath was a valid DID).
But, as you can probably tell by the length of that issue, there's no community consensus for doing that.

So, you're absolutely right to want to fix it so that it matches the current spec. I'll make a new release.

[dmitrizagidulin]

👍

[dmitrizagidulin]

@zscott - @interop/[email protected] published to npm.

[zscott]

@dmitrizagidulin thanks for the incredibly quick response! I agree with you that / makes more sense for delimiting paths, but my focus is on getting something to work in an interoperable way. I appreciate the merge. Thanks!