Add wrapper around move_uploaded_file

src/MD_STD.php

@@ -679,4 +679,23 @@ final class MD_STD {
         return $code;
 
     }
+
+    /**
+     * Checks if a directory is writable.
+     *
+     * @param string $dir Directory path.
+     *
+     * @return void
+     */
+    public static function check_is_writable(string $dir):void {
+
+        if (is_dir($dir) === false) {
+            throw new MDFileDoesNotExist("Directory " . $dir . " does not exist");
+        }
+
+        if (is_writable($dir) === false) {
+            throw new MDFileIsNotWritable("Directory " . $dir . " is not writable");
+        }
+
+    }
 }