Add SyncedResourceDeleted event and DeleteResourceMapping listener

Also move pivot record deletion to that listener and improve tests

src/ResourceSyncing/Events/SyncedResourceDeleted.php

@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Stancl\Tenancy\ResourceSyncing\Events;
+
+use Illuminate\Database\Eloquent\Model;
+use Stancl\Tenancy\Database\Contracts\TenantWithDatabase;
+use Stancl\Tenancy\ResourceSyncing\Syncable;
+
+class SyncedResourceDeleted
+{
+    public function __construct(
+        public Syncable&Model $model,
+        public TenantWithDatabase|null $tenant,
+        public bool $forceDelete,
+    ) {}
+}