Tweak Microsoft AD search in auth-ldap

[gerundt]

Currently search the auth-ldap plugin with Microsoft Active Directory connections only for login name and display name.

For first name (givenName) and last name (sn) was the wrong attributes used. I also added the mail address (mail) as addional search attribute.

[ChrisTG742]

Some "advanced configuration" option (normally hidden) to directly customize the search-filter-strings would be great here.
I'd think of something like buttons that make textfields visible that contain the whole search-filters:
search: (&(objectClass=inetOrgPerson)(|(uid={q}*)(displayName={q}*)(cn={q}*)))
lookup: (&(objectClass=inetOrgPerson)({attr}={q}))
However, this needs code changes in the admin-GUI, too.