MDL-63211 core: deprecated events for blocking/unblocking contacts

The message_contact_blocked and message_contact_unblocked
events were deprecated. The reason being that you will be
able to block and unblock any user, regardless if they are
a contact or not. This information is also now stored in a
separate DB table.

lib/classes/event/message_contact_blocked.php

@@ -26,6 +26,9 @@ namespace core\event;
 
 defined('MOODLE_INTERNAL') || die();
 
+debugging('core\\event\\message_contact_blocked has been deprecated. Please use
+        core\\event\\message_user_blocked instead', DEBUG_DEVELOPER);
+
 /**
  * Message contact blocked event class.
  *
@@ -99,4 +102,13 @@ class message_contact_blocked extends base {
         // Messaging contacts are not backed up, so no need to map them on restore.
         return array('db' => 'message_contacts', 'restore' => base::NOT_MAPPED);
     }
+
+    /**
+     * This event has been deprecated.
+     *
+     * @return boolean
+     */
+    public static function is_deprecated() {
+        return true;
+    }
 }

lib/classes/event/message_contact_unblocked.php

@@ -26,6 +26,9 @@ namespace core\event;
 
 defined('MOODLE_INTERNAL') || die();
 
+debugging('core\\event\\message_contact_unblocked has been deperecated. Please use
+        core\\event\\message_user_unblocked instead', DEBUG_DEVELOPER);
+
 /**
  * Message contact unblocked event class.
  *
@@ -99,4 +102,13 @@ class message_contact_unblocked extends base {
         // Messaging contacts are not backed up, so no need to map them on restore.
         return array('db' => 'message_contacts', 'restore' => base::NOT_MAPPED);
     }
+
+    /**
+     * This event has been deprecated.
+     *
+     * @return boolean
+     */
+    public static function is_deprecated() {
+        return true;
+    }
 }