[feat] Progress reporting for HTTP API in JS

### Describe the problem

When using the Tauri HTTP API, I'd like to know how much of a file is downloaded so that I can create a progress bar in my app.

### Describe the solution you'd like

It would be nice if the HTTP api's fetch function could take a progress callback.

### Alternatives considered

Another option is to provide access to a `ReadableStream` object as a response type, allowing the developer to access data as it becomes available.

### Additional context

_No response_