Add progress bar while applying upgrades

Originally created by @sajolida on #17314 (Redmine)

When upgrading from 4.0 to 4.1, I got a dialog with a progress bar that was full straight away and didn’t move at all.

See screenshot in attachment.

This adds confusion to #17312.

Edited May 21, 2020 by sajolida

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information