Give warning if no installation is selected, or if the user does not have access to the installation

[andchiind]

Describe the improvement you would like to see
If we are on the front page and no installation is chosen, it can be hard to understand why nothing is working. Therefore, there should be a banner or dialog telling the user to select an installation. The same should happen if the user has selected an installation they do not have access to.

How will this change existing functionality?
It will make the website more easy to use.

How will this improvement affect the current Threat Model?
N/A

[andchiind]

A part of this fix could also be to add installation code to the URL path after we leave the installation selection page.