Investigate how we can support for writing back relations in LDAPService::updateLDAPFromMember

[sabina-talipova]

Description

SilverStripe\Security\Member.ldap_field_mappings defines the AD attributes that should be mapped to Member fields. We must implement logic for the case if instance of Member class has relationships has_one, has_many, etc.
See

silverstripe-ldap/src/Services/LDAPService.php

Lines 975 to 982 in df528fe

	foreach ($member->config()->ldap_field_mappings as $attribute => $field) {
	$relationClass = $member->getRelationClass($field);
	if ($relationClass) {
	// todo no support for writing back relations yet.
	} else {
	$attributes[$attribute] = $member->$field;
	}
	}