Delete the user in a GDPR compatible way (#1151)

* Delete the user in a GDPR compatible way

* Block user from calls

* Style fix

app/Exceptions/UserNotFound.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace App\Exceptions;
+
+class UserNotFound extends AbstractHttpException
+{
+    public function __construct()
+    {
+        parent::__construct(
+            404,
+            'User not found'
+        );
+    }
+
+    /**
+     * Return the RFC 7807 error type (without the URL root)
+     */
+    public function getErrorType(): string
+    {
+        return 'user-not-found';
+    }
+
+    /**
+     * Get the detailed error string
+     */
+    public function getErrorDetails(): string
+    {
+        return $this->getMessage();
+    }
+
+    /**
+     * Return an array with the error details, merged with the RFC7807 response
+     */
+    public function getErrorMetadata(): array
+    {
+        return [];
+    }
+}