Move the dependency calculation helper methods from ConfigEntityBase to generic traits

+++ b/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php
@@ -22,6 +23,10 @@
+  use PluginDependencyTrait {
+    addDependency as addDependencyTrait;
+  }

@@ -364,44 +342,8 @@ protected function addDependency($type, $name) {
     if ($type == 'module' && ($name == $this->getEntityType()->getProvider() || $name == 'Core')) {
       return $this;
     }
...
+    return $this->addDependencyTrait($type, $name);

Because we want to do this entity-specific check before adding dependencies, we need to do this aliasing trick with traits.

We have no standard way to document this pattern, but while it seems weird now, it will become more common as we become more familiar with traits.

+++ b/core/modules/user/lib/Drupal/user/Plugin/Action/ChangeUserRoleBase.php
@@ -80,12 +83,11 @@ public function submitConfigurationForm(array &$form, array &$form_state) {
-      $dependencies['entity'][] = $prefix . $this->configuration['rid'];
+      $this->addDependency('entity', $prefix . $this->configuration['rid']);

When I added this code to user roles initially, I remember being very confused about the nesting of the dependencies. This method makes it that much easier