Auto select one and only cluster from pasted config (#888)

* Auto select one and only cluster from pasted config

- Disable add button with tooltip if no clusters are selected
- Add functionality to tooltip to display correctly over disabled
  elements

* feature should work of any method of adding kube config

Signed-off-by: Sebastian Malton <sebastian@malton.name>
Co-authored-by: Sebastian Malton <smalton@mirantis.com>

integration/specs/app_spec.ts

@@ -17,10 +17,6 @@ describe("app start", () => {
   const addMinikubeCluster = async (app: Application) => {
     await app.client.click("div.add-cluster")
     await app.client.waitUntilTextExists("div", "Select kubeconfig file")
-    await app.client.click("div.Select__control")
-    await app.client.waitUntilTextExists("div", "minikube")
-    await app.client.click("div.minikube")
-    await app.client.click("div.Select__control")
     await app.client.click("button.primary")
   }