Add "Loading" Indicator that Prevents Re-Submission

We should have a MaterialUI loading wheel (progress wheel) that will appear following submission while waiting for the async response to come back to the frontend. This should pop up as a dialog window and tell the user that the photos are being uploaded, at the same time, the submit button should be disabled and the dialog window should not be "closeable".

Reference: https://mui.com/material-ui/react-progress/