fix(openapi): multi-level group route .openapi() parsing

[mrsafalpiya]

Consider the following contents of the start/routes.ts file:

router.group(() => {
  router.group(() => {
    router.get("/foo")
      .openapi({  // OpenAPI options of actual route (3rd level)
        responses: {
          "403": {
            ...
          },
        },
      });
  }).openapi({  // OpenAPI options of 2nd level group
    responses: {
      "402": {
        ...
      },
    },
  });
}).openapi({  // OpenAPI options of 1st level group
  responses: {
    "401": {
      ...
    },
  },
});

For readability, the above routes can be viewed in POV of HTML tags as:

<Group openapi={{ responses: { '401': ... } }}>
     <Group openapi={{ responses: { '402': ... } }}>
         <Route get="/foo" openapi={{ responses: { '403': ... } }} />
     </Group>
 </Group>

Previously, the openapi options of the 1st level group was ignored i.e. 401 response. So only 402 and 403 responses were parsed.

This PR fixes the above bug for any group route level by using recursive function to parse group routes.