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/command-palette/command-dialog.tsx

@@ -4,7 +4,7 @@ import { computed, observable, toJS } from "mobx";
 import { observer } from "mobx-react";
 import React from "react";
 import { commandRegistry } from "../../../extensions/registries/command-registry";
-import { clusterStore } from "../../../common/cluster-store";
+import { ClusterStore } from "../../../common/cluster-store";
 import { CommandOverlay } from "./command-container";
 import { broadcastMessage } from "../../../common/ipc";
 import { navigate } from "../../navigation";
@@ -20,7 +20,7 @@ export class CommandDialog extends React.Component {
     };
 
     return commandRegistry.getItems().filter((command) => {
-      if (command.scope === "entity" && !clusterStore.active) {
+      if (command.scope === "entity" && !ClusterStore.getInstance().active) {
         return false;
       }