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/+catalog/catalog.tsx

@@ -11,7 +11,7 @@ import { MenuItem, MenuActions } from "../menu";
 import { Icon } from "../icon";
 import { CatalogEntityContextMenu, CatalogEntityContextMenuContext, catalogEntityRunContext } from "../../api/catalog-entity";
 import { Badge } from "../badge";
-import { hotbarStore } from "../../../common/hotbar-store";
+import { HotbarStore } from "../../../common/hotbar-store";
 import { autobind } from "../../utils";
 import { Notifications } from "../notifications";
 import { ConfirmDialog } from "../confirm-dialog";
@@ -57,7 +57,7 @@ export class Catalog extends React.Component {
   }
 
   addToHotbar(item: CatalogEntityItem) {
-    const hotbar = hotbarStore.getByName("default"); // FIXME
+    const hotbar = HotbarStore.getInstance().getByName("default"); // FIXME
 
     if (!hotbar) {
       return;
@@ -67,7 +67,7 @@ export class Catalog extends React.Component {
   }
 
   removeFromHotbar(item: CatalogEntityItem) {
-    const hotbar = hotbarStore.getByName("default"); // FIXME
+    const hotbar = HotbarStore.getInstance().getByName("default"); // FIXME
 
     if (!hotbar) {
       return;