XWIKI-10481: implement avatar synchronization in ldap-authentificator

.../main/java/com/xpn/xwiki/plugin/ldap/XWikiLDAPConfig.java

...n/java/com/xpn/xwiki/plugin/ldap/XWikiLDAPConnection.java

...a/com/xpn/xwiki/plugin/ldap/XWikiLDAPSearchAttribute.java

...c/main/java/com/xpn/xwiki/plugin/ldap/XWikiLDAPUtils.java

...tform-ldap-ui/src/main/resources/XWiki/AdminLdapSheet.xml

...ternal/mandatory/XWikiPreferencesDocumentInitializer.java

...ldcore/src/main/resources/ApplicationResources.properties

...tion-flavor/src/main/resources/XWiki/XWikiPreferences.xml

...l-configuration-resources/src/main/resources/xwiki.cfg.vm