Make liboauth dependency optional and disabled by default
See the commit messages. Briefly, this:
- Makes the liboauth dependency optional, since OAuth 1.0 has been deprecated since 2012
- Disables it by default because liboauth hasn’t built properly upstream for a few years
- Unconditionally drops OAuth 1.0 support from the GOA authorizer, since only OAuth 2.0 is used in practice for the services we support
Closes #1 (closed)