Entity share: Add support for Configuration entities

Problem/Motivation

When using entity sharing in Drupal, it's important to note that configuration entities, such as contact forms, not be fully supported in the same way as content entities. This guide outlines a specific issue where configuration entities are not synchronised as expected between an entity share server and client.

Steps to reproduce

Entity Share Server Site:

1. Log in to the entity share server site.
2. Create a content that includes a form field with a reference type (config form).
3. Add form fields and other necessary details.
4. Click on Save to save the content.

Entity Share Client Site:

1. Log in to the entity share client site.
2. Navigate to /admin/content/entity_share/pull.
3. Filter the content channel.

Observation:

Observe that the content with the form field is listed accordingly.

Synchronize Entities:

1. Select the appropriate content.
2. Click on "Synchronize entities."

View Local:

After synchronization, click on "View Local."
Observe that the form field details, especially those with reference types (config form), are not pulled from the server to the client as expected.