added import and export recurring bills

app/Exports/Purchases/RecurringBills/Sheets/Recurring.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace App\Exports\Purchases\RecurringBills\Sheets;
+
+use App\Abstracts\Export;
+use App\Models\Common\Recurring as Model;
+
+class Recurring extends Export
+{
+    public function collection()
+    {
+        return Model::bill()->cursor();
+    }
+
+    public function map($model): array
+    {
+        $model->bill_number = $model->recurable->document_number;
+                
+        return parent::map($model);
+    }
+
+    public function fields(): array
+    {
+        return [
+            'recurable_type',
+            'bill_number',
+            'frequency',
+            'interval',
+            'started_at',
+            'status',
+            'limit_by',
+            'limit_count',
+            'auto_send',
+        ];
+    }
+}