MDL-77350 availability: Added class properties that are not declared

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.

availability/condition/completion/classes/frontend.php

@@ -37,7 +37,7 @@ class frontend extends \core_availability\frontend {
     /**
      * @var array Cached init parameters
      */
-    protected $cacheparams = [];
+    protected $cacheinitparams = [];
 
     /**
      * @var string IDs of course, cm, and section for cache (if any)