o Minor features (IPv6, v3 onion services):
    - Make v3 onion services put IPv6 addresses in service
      descriptors. Before this change, service descriptors only
      contained IPv4 addressesd. Implements 26992.
  o Code simplification and refactoring:
    - Simplify v3 onion service link specifier handling code.
      Fixes bug 23576; bugfix on 0.3.2.1-alpha.