Allow to ClientDataToEntityConverter to handle ComponentTreeEntityInterface entities

Overview

In 📌 Refactor ApiLayoutController into 2 sub-class to support Content Templates Active we started update ClientDataToEntityConverter to handle not only fieldable entities but also content template. It turns all we needed was to use ClientServerConversionTrait directly in the case we are dealing with ContentTemplate entities.

So decided to create this issue to update ClientDataToEntityConverter because along with that the test coverage ClientDataToEntityConverterTest should also be updated.

Proposed resolution

Allow \Drupal\experience_builder\ClientDataToEntityConverter::convert to update ContentTemplate entities and possibly other ComponentTreeEntityInterface entities. Update \Drupal\experience_builder\Controller\ApiLayoutController::buildPreviewRenderable to not use `\Drupal\experience_builder\Controller\ClientServerConversionTrait::convertClientToServer` directly

User interface changes