Configurable activity and project number (#4729)

* added configurable activity number
* added configurable project number
* fix deprecations
* added some tests for entity exporter
* better configuration of dropdown pattern for customer, project and activity

src/Entity/Customer.php

@@ -475,7 +475,7 @@ class Customer implements EntityWithMetaFields, EntityWithBudget
 
     public function __clone()
     {
-        if ($this->id) {
+        if ($this->id !== null) {
             $this->id = null;
         }