When `timeout` option is provded, we need to set a custom abort controller. This means using `timeout` and `controller` are mutually exclusive. ([src](https://github.com/unjs/ofetch/blob/bb2d72baa5d3f332a2185c20fc04e35d2c3e258d/src/fetch.ts#L152)). I am thinking if there is (low cost) solution to merge signals