- Show Knative install button on group/instance cluster pages
- Allow Knative to be installed on group/instance clusters
- Add feature specs for installing applications on group/instance
  clusters
- Add changelog entry
- Update docs to reflect that Knative can now be installed on
  group-level and instance-level clusters

Use update term instead of update in the clusters managed app
implementation in order to make the implementation and UI
language more consistent.

The new component also implements several improvements in the
knative domain editor workflow:

- Display a loading spinner when saving changes in the domain name
- Display success toast message indicating changes were saved
successfully.
- Display error message in the contraty occurs

- Vue confirmation modal implementation
- CSS tweaks for modal default height

- Separate cluster application UI state from server-side app status
- Use a state machine to determine cluster application next state
- Instead of using two variables to keep track of when an app
is installing or updating, just use the app status property and control
server-side and user events using the FSM service.

A runner installed on a cluster will now use the
cluster's `cluster_type` as its `runner_type`.

Show a loading spinner while Ingress/Knative IP is being assigned

Added the functionality to edit the Knative domain