Config schema errors for entity types not listed in entity_clone.settings.schema.yml

Rerolled patch for 2.x

+++ b/tests/src/Kernel/EntityCloneEntityTypeSettingsTest.php
@@ -0,0 +1,36 @@
+    $entity_clone_settings->set('form_settings', $form_settings)->save();

The test should add an assert. Something like the following would probably be enough:

    try {
      $result = $this->configImporter()->validate();
      $this->assertInstanceOf(ConfigImporter::class, $result);
    }
    catch (ConfigImporterException $e) {
      $this->fail('A ConfigImporterException was thrown. This should not happen.');
    }

The MR is simply a rehash of the latest patch. Can we add the requested test coverage too?

Added assertion to EntityCloneEntityTypeSettingsTest but now got it failed