Fixing Singleton typing to correctly return child class (#1914)

- Add distinction between `getInstance` and `getInstanceOrCreate` since
  it is not always possible to create an instance (since you might not
  know the correct arguments)

- Remove all the `export const *Store = *Store.getInstance<*Store>();`
  calls as it defeats the purpose of `Singleton`. Plus with the typing
  changes the appropriate `*Store.getInstance()` is "short enough".

- Special case the two extension export facades to not need to use
  `getInstanceOrCreate`. Plus since they are just facades it is always
  possible to create them.

- Move some other types to be also `Singleton`'s: ExtensionLoader,
  ExtensionDiscovery, ThemeStore, LocalizationStore, ...

- Fixed dev-run always using the same port with electron inspect

- Update Store documentation with new recommendations about creating
  instances of singletons

- Fix all unit tests to create their dependent singletons

Signed-off-by: Sebastian Malton <sebastian@malton.name>

src/renderer/components/+workloads-statefulsets/statefulset-details.tsx

@@ -19,7 +19,7 @@ import { PodDetailsList } from "../+workloads-pods/pod-details-list";
 import { KubeObjectMeta } from "../kube-object/kube-object-meta";
 import { kubeObjectDetailRegistry } from "../../api/kube-object-detail-registry";
 import { ResourceType } from "../cluster-settings/components/cluster-metrics-setting";
-import { clusterStore } from "../../../common/cluster-store";
+import { ClusterStore } from "../../../common/cluster-store";
 
 interface Props extends KubeObjectDetailsProps<StatefulSet> {
 }
@@ -48,7 +48,7 @@ export class StatefulSetDetails extends React.Component<Props> {
     const nodeSelector = statefulSet.getNodeSelectors();
     const childPods = statefulSetStore.getChildPods(statefulSet);
     const metrics = statefulSetStore.metrics;
-    const isMetricHidden = clusterStore.isMetricHidden(ResourceType.StatefulSet);
+    const isMetricHidden = ClusterStore.getInstance().isMetricHidden(ResourceType.StatefulSet);
 
     return (
       <div className="StatefulSetDetails">