Deprecate SpringSecurityLdapTemplate

[jzheaux]

SpringSecurityLdapTemplate exposes many operations that are available in modern-day Spring LDAP by way of LdapClient and LdapQueryBuilder. We should try and replace usage of SpringSecurityLdapTemplate with Spring LDAP's default LdapClient implementation to simplify maintenance and configuration.

• Change PasswordComparisonAuthenticator to use LdapClient
• Change FilterBasedLdapUserSearch to use LdapClient
• Change ActiveDirectoryLdapAuthenticationProvider to use LdapClient
• Add an LdapAuthoritiesPopulator implementation that uses LdapClient
• Deprecate SpringSecurityLdapTemplate