Set default value for components that properly validates

STR? Test?

We've got very thorough validation in place, so I don't see how this is possible, unless we're doing $page = Page::create(); followed by ->save() without first doing ->validate().

The code was:

    $page = $this->entityTypeManager->getStorage('xb_page')->create([
      'title' => $title,
      'uuid' => $uuid,
      'path' => [['alias' => $path]],
      'status' => TRUE,
    ]);
    $page->save();

Which is what a lot of developers may do, since most do not call `validate` before saving. I have a feeling people will programmatically create the entities and while technically invalid expect them to work without XB crashing.

This has long since been fixed, and ever since 📌 [PP-1] Consider not storing the ComponentTreeStructure data type as a JSON blob Postponed looks quite different. This is obsolete :)