feat(web/server): webp thumbnail size configurable (#3598)

* feat(server/web): webp thumbnail size configurable

* update api

* add ui and fix test

* lint

* setting for jpeg size

* feat: coerce to number

* api

* jpeg resolution

---------

Co-authored-by: Jason Rasmussen <jrasm91@gmail.com>

mobile/openapi/test/system_config_dto_test.dart

@@ -41,6 +41,11 @@ void main() {
       // TODO
     });
 
+    // SystemConfigThumbnailDto thumbnail
+    test('to test the property `thumbnail`', () async {
+      // TODO
+    });
+
 
   });