Design: Upload Progress Bar/Buffer Wheel

[danglorioso]

Describe the issue

Uploading new data can take up to a few minutes. Currently, there isn't any feedback to the user that data is actually being uploaded.

Where Is the Issue / How to Recreate

Steps to reproduce the behavior:

1. Go to upload page
2. Attach a valid spreadsheet
3. Get to the final step and upload

Suggested fix(es):

• Easiest: add a buffer wheel that spins while data is being uploaded
• Better: add a progress bar that estimates when the data would finish uploading

[tika]

If processing runs on the server, we could have a status/loading animation on the years upload tab. Since data will not be required immediately, this may provide the best UX - the user doesn't have to wait for the data to upload (fragile) and we can notify them when the data has been uploaded