MDL-78142 lib: Added class properties that are not declared in bennu

In PHP 8.2 and later, setting a value to an undeclared class property is
deprecated and emits a deprecation notice.
So we need to add missing class properties that still need to be declared.

lib/bennu/iCalendar_properties.php

@@ -25,6 +25,12 @@ class iCalendar_property {
     var $val_multi        = false;
     var $val_default      = NULL;
 
+    /** @var int|null RFC2445_TYPE value. */
+    protected $val_type;
+
+    /** @var string property name. */
+    protected $name;
+
     function __construct() {
         $this->parameters = array();
     }

lib/bennu/readme_moodle.txt

@@ -30,3 +30,4 @@ Changelog
 11/ MDL-67029: replace curly by square brackets for string offsets. PHP 7.4 compatibility (25 Oct 2019)
 12/ MDL-74866: fixed parameter parsing if the value is wrapped by DQUOTE character (28 Jul 2022)
 13/ MDL-76333: replaced strftime() with date() for PHP 8.1 compatibility (16 Nov 2022)
+14/ MDL-78142: fixed PHP 8.2: Dynamic Properties deprecations (9 May 2023)