Improve logging for the m_ldap and m_ldapauth modules (#1757).

Improve logging for the m_ldap and m_ldapauth modules (#1757).

Currently, it is difficult to diagnose LDAP authentication failures,
since the logs do not provide sufficient information about what is
actually being queried and what actually failed.

This increases logging details so that information about the LDAP query
is included, for example:

  Fri Mar 06 2020 08:02:59 ANNOUNCEMENT: Error binding as manager to LDAP
  server: Invalid credentials (bind dn=cn=adminz,dc=nodomain)

Rather than:

  Fri Mar 06 2020 08:02:59 ANNOUNCEMENT: Error binding as manager to LDAP
  server: Invalid credentials

Same with connection logging:

  Fri Mar 06 2020 07:59:53 CONNECT: Forbidden connection from
  jsing!jsing@192.168.200.1 (Invalid credentials (bind
  dn=uid=jsing,dc=nodomain))

  Fri Mar 06 2020 08:01:19 CONNECT: Successful connection from
  jsing!jsing@192.168.200.1 (dn=uid=jsing,dc=nodomain)