Add let option to explain delete

Author: GromNaN

src/Operation/Delete.php

@@ -177,7 +177,11 @@ public function execute(Server $server)
      */
     public function getCommandDocument()
     {
-        return ['delete' => $this->collectionName, 'deletes' => [['q' => $this->filter] + $this->createDeleteOptions()]];
+        $cmd = ['delete' => $this->collectionName, 'deletes' => [['q' => $this->filter] + $this->createDeleteOptions()]];
+        $cmd += $this->createBulkWriteOptions();
+        unset($cmd['comment']);
+
+        return $cmd;
     }
 
     /**

tests/Operation/DeleteTest.php

@@ -88,6 +88,7 @@ public function testExplainableCommandDocument(): void
                     'hint' => '_id_',
                 ],
             ],
+            'let' => (object) ['a' => 1],
         ];
         $this->assertEquals($expected, $operation->getCommandDocument());
     }