Client side authentication for HSv3

Thanks to mig5 adding support for tor's new ONION_CLIENT_AUTH_ADD,
ONION_CLIENT_AUTH_REMOVE, and ONION_CLIENT_AUTH_VIEW features. These
add support for authenticating *to* a version 3 hidden service.

  https://github.com/torproject/stem/issues/66

Implementation uncovered some rough edges within tor...

  * Controllers cannot create authenticated services

    tpo/core/tor#40084

  * Client names apparently don't work

    tpo/core/tor#40089

  * Credential persistence either doesn't work or vague error response

    tpo/core/tor#40090