Empty state deployment board, can't find application

If there's no deployment for an app, we show 100% complete with no instances. Instead show an empty state that we couldn't find that application.

The empty state of the deploy board should probably only include what needs to be set up for deploy boards to work, so technically I think that means that deployments need to be labeled with app=$CI_ENVIRONMENT_SLUG in the unique namespace specified in the kubernetes service setting (which we know at this point, so can echo as well). Or do replica sets need app= as well? I'm assuming replica sets and pods need that label for terminal to work, but not for deploy boards. The k8s service itself should list it all, of course, but be explicit about which needs which.

image for reference:

Design

spec export

text should state:

Kubernetes deployment not found `To see deployment progress for your environments, ... (same as in the mockup)

cc: @ayufan @grzesiek @markpundsack @filipa