Show loading spinner while Ingress/Knative IP is being assigned

What does this MR do?

This MR ensures that a loading spinner is displayed instead of a ? while the Ingress/Knative IP is being assigned

What are the relevant issue numbers?

Closes #49863 (closed)

Closes #56945 (closed)

Preview

before	after

To simulate the "loading" state, the following commands can be executed:

Open rails console: bundle exec rails console

In rails console execute the following:

1. cluster = Clusters::Cluster.find <id> Note: <id> can be found in the browser url when navigating to the cluster
2. ingress = cluster.application_ingress OR knative = cluster.application_knative to test Knative
3. ingress.update!(external_ip: nil) OR knative.update!(external_ip: nil) to test Knative

Ingress/Knative should temporarily be without an external endpoint and should display the loading icon for a few seconds until the IP is retrieved again.

Repeat step 1-3 again in order to simulate the same behaviour again.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides