Layout builder integration

Although this patch (#24) works, it implicates the json-api extra settings need to be "opened" up, client side in order for the route to be known so it can be constructed. Otherwise you get a unknown route error on your client.

// Build route name
$routeName = sprintf('jsonapi.%s--%s.individual', 'block_content', $configuration['block_bundle']);

// Since we're calling Url::fromRoute() on the importing site, we need to replace the host with the remote's host
$self_link = Url::fromRoute($routeName, ['entity' => $configuration['block_uuid']], ['absolute' => TRUE])->toString();

- Creating MR
- testing patches since the last time I did it
- updating patch

I have tested on a Core 10.2.7 with the following patch: #2942975-255: [PP-1] Expose Layout Builder data to REST and JSON:API →

Enabling the field enhancer on both client and server sites. And enabling the "Layout builder" processor in the config import.

It is working well.

Now that a MR had been created, code review and rebase will be easier.