Generate Automatic Error if user uploads files above supported limit, or corrupted files#271

For file uploads questions, there is currently a 16MB total limit to files that can be uploaded within a single session. If user exceeds that limit, or uploads a file that Gavel reads as corrupted, the user is only met with the default error page at the end of the workflow.

It’s currently hard for the end-user/external client to be able to understand what the error is with the default error page, and they would have to restart an entirely new session.

It would be useful to either automatically indicate that there is an error with the uploaded file right away, or have an error pop up when the user has exceeded the file limit as soon as that error occurs in the workflow, so that the user can correct the error right away, without having to retart an entire intake after seeing that error at the end.