Add a checkbox to the LDAP auth configuration UI to "Always Search"
Summary: Fixes T3208. This forces us to bind+search even if there are no anonymous credentials.
Test Plan: Checked the box, saved the form. Unchecked the box, saved the form. LDAP??
Reviewers: Firehed
Reviewed By: Firehed
Subscribers: epriestley
Maniphest Tasks: T3208
Differential Revision: https://secure.phabricator.com/D8723