Improve error messaging when deploy fails

Hi, can a catch block be added to this function so there is a better explanation when the deployment fails due to corrupted files or just the request failing (it actually returns 400 error but with the message "Error: Unexpected error while uploading file.", which is not very handy).

https://github.com/firebase/firebase-tools/blob/40afb70e9626efe526e46697f9847d1a92c47e06/src/deploy/hosting/uploader.js#L187

Start in src/deploy/hosting/uploader.js around line 187, as linked in the issue, and inspect how upload failures are currently reported. Reproduce or trace the 400 response and corrupted-file failure cases, then make sure the resulting deployment error explains which failure occurred instead of only saying "Unexpected error while uploading file."

Written by the indexing model from the issue text.