Update Backup & Restore

[j-lindner]

Changes

• copied starting point from https://github.com/ManuelDittmar/backup-restore-demo
• Restructured folder structure
• --version on helm install
• added helm uninstall to cleanup
• Downloaded used files (instead of wget-ing them)
• Changed Validation: Cancel via Operate UI
• Added 'bash' to ```bash, so it's clickable in IntelliJ
• Correctd echo: "Restore completed for snapshot: $snapshot in repository: $repository" instead of "Restore initiated [...]"

Please also check the updated Slides
Slides 40 - 42: https://docs.google.com/presentation/d/1dWxsri2rKUPGqSGoXg7QQrzLSV-ZmnsodgclZEz4FZ4/edit#slide=id.g251fdc97518_0_24
--> Please add comments there and/or here. If everything looks good, please resolve the comment on the Slides directly. Thanks!

[jonathanlukas]

I gave some hints. If they cannot be done in time, we can create issues for them.