Minor schema cosmetic code fixes, more Attribute implementation from old pla, start of LDAP DN view/edit

app/Classes/LDAP/Attribute/Internal.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace App\Classes\LDAP\Attribute;
+
+use App\Classes\LDAP\Attribute;
+
+/**
+ * Represents an attribute whose values are internal
+ */
+abstract class Internal extends Attribute
+{
+	protected bool $internal = TRUE;
+}