Improve UX when Rancher API requests fail to respond on fresh load of the UI

[richard-cox]

Is your feature request related to a problem? Please describe.

• When waiting for initial api requests to rancher to respond we show a blank page and a spinning loading icon
• There are times though when the api requests will time out / fail
• In those cases we just continue to show the spinning icon

Describe the solution you'd like

• We need to notify the user of the failure and give some suggestions on next steps

Additional context

• In development this can happen, but also out in the wild
• Adding better notifications will help users to resolve the issue via the rancher instance rather than the UI itself