chore: Remove SecureLink.encryptionMethod as per #450
Created by: un-cefact-github-app[bot]
Remove SecureLink.encryptionMethod. See https://github.com/uncefact/spec-untp/issues/450
This property was also a blocker to #408 (closed) - updating our link/securelink to use the digestMultibase which is already included and used with VC's and more generally in the community, rather than our own specific version with hashDigest and hashMethod.
As the first change after the 0.6.1 release, this PR also switches back to working URLs.