Serve UUI with HTTPS through Gitweb

Now that we have https://git-tails.immerda.ch/uui-binary we could serve UUI with HTTPS through Gitweb. This would protect our users from simple MitM.

Feature Branch: web/10575-uui-gitweb

Original created by @sajolida on 10575 (Redmine)

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