feat(core): add system store service interface

Signed-off-by: Sebastian Krupinski <krupinski01@gmail.com>

shared/lib/SystemStore/Provider/ProviderBaseInterface.php

@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace KTXF\SystemStore\Provider;
+
+use KTXF\Resource\Provider\ResourceProviderBaseInterface;
+
+/**
+ * Provider for tenant-scoped internal storage services.
+ */
+interface ProviderBaseInterface extends ResourceProviderBaseInterface
+{
+    public const JSON_TYPE = 'system-store:provider';
+}