improve UI for compute resource overview page

[timogoebel]

In #81 an overview page was added to find VMs that are associated with the wrong compute resource, missing on a compute resource or duplicate hosts that refer to a single VM.

We should improve the visual appearance, add links to the host view page and add buttons to fix the association where applicable.

[kamils-iRonin]

@timogoebel Can you describe how the buttons to fix the association should work?

[timogoebel]

@kamils-iRonin: They can just use this functionality: https://github.com/theforeman/foreman/blob/ae96cb70130968bdcc8b7a9a9af7edc7c6e0d9a8/app/services/compute_resource_host_associator.rb#L20-L29