[UI] Progress is always stuck at 0% during uploading

**Describe the bug**
Progress is always stuck at 0% during uploading.

**To Reproduce**
1. Go to "Data" section.
2. Upload a file in a file group.
3. Open "Activity Monitor".
4. Observe that upload progress is always 0%.

**Expected behavior**
The progress will reflect the upload progress like Azure Web Portal does.

**Logs**
app.log is empty.
[client.log](https://github.com/Azure/BatchExplorer/files/5904488/client.log)

**Version**
- OS: Windows
- Version 19042.746