Upload progress

Can i get upload progress when upload a string like this ?

```node

import { getStorage, ref, uploadString } from "firebase/storage";

const storage = getStorage();
const storageRef = ref(storage, 'some-child');

// Data URL string
const message4 = 'data:text/plain;base64,5b6p5Y+344GX44G+44GX44Gf77yB44GK44KB44Gn44Go44GG77yB';
const uploadTask = uploadString(storageRef, message4, 'data_url')

uploadTask.on('progress',()=>{
//get progress
})

```

Start by checking the Firebase Storage web API documentation for uploadString and the returned upload task's event methods. Determine whether progress reporting is supported for this upload form; done means the issue has a documented, verified answer or a clearly scoped change request.

Written by the indexing model from the issue text.