LDAP authentication incompatible with basic_auth authentication provider

Authenticating via basic authentication is a process which can be useful to third-party services to, for example, consume REST API instead of using cookies.

When LDAP is enabled, the basic_auth module cannot also be enabled or logins are no longer possible.

A possible source of the problem is the ordering of authentication providers:
- { name: authentication_provider, provider_id: 'basic_auth', priority: 100 }

This requires additional testing to isolate the cause and we need to define how we want this to work in exclusive as well as mixed mode.