[mysql] Add stubs for mysqli, mysqli_stmt and mysqli_result cla…

…sses

stubs/extensions/mysqli.phpstub

@@ -1,12 +1,25 @@
 <?php
 
+class mysqli
+{
+    /**
+     * @var int<-1, max>|numeric-string
+     */
+    public $affected_rows;
+}
+
 /**
  * @template TValue
  *
  * @template-implements Traversable<int, TValue>
  */
 class mysqli_result implements Traversable
 {
+    /**
+     * @var int<0, max>|numeric-string
+     */
+    public $num_rows;
+
     /**
      * @psalm-taint-sink callable $class
      *
@@ -18,6 +31,53 @@ class mysqli_result implements Traversable
     function fetch_object(string $class = stdClass::class, array $constructor_args = []): object|false|null {}
 }
 
+lass mysqli_stmt
+{
+    /**
+     * @var int<-1, max>|numeric-string
+     */
+    public $affected_rows;
+
+    /**
+     * @var int
+     */
+    public $errno;
+
+    /**
+     * @var list<array{errno: int, sqlstate: string, error: string}>
+     */
+    public $error_list;
+
+    /**
+     * @var string
+     */
+    public $error;
+
+    /**
+     * @var 0|positive-int
+     */
+    public $field_count;
+
+    /**
+     * @var int|string
+     */
+    public $insert_id;
+
+    /**
+     * @var int<0,max>|numeric-string
+     */
+    public $num_rows;
+
+    /**
+     * @var 0|positive-int
+     */
+    public $param_count;
+
+    /**
+     * @var non-empty-string
+     */
+    public $sqlstate;
+}
 
 /**
  * @psalm-taint-sink callable $class