Remove pf::Portal::Profile->getGuestCategory

The category (aka role) of users is defined in the authentication
sources and the local SQL-based source.
Update gaming registration page for new auth
Localization
Adapt code for new email authentication source

External authentication sources (ie oauth2, email, and sms) are defined
as unique authentication sources (only one instance of each type can be
configured). For those sources, we have two new methods:
getAuthenticationSourceByType and matchByType. The "type" argument must
match the "type" attribute of one of the external authentication
sources.