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/extensions/registries/__tests__/page-registry.test.ts

@@ -1,6 +1,10 @@
 import { getExtensionPageUrl, globalPageRegistry, PageParams } from "../page-registry";
 import { LensExtension } from "../../lens-extension";
 import React from "react";
+import { Console } from "console";
+import { stdout, stderr } from "process";
+
+console = new Console(stdout, stderr);
 
 let ext: LensExtension = null;