[MM-51874] Migrate loading screen to singleton (#2655)

* Migrate loadingScreen to singleton

* REVERT ME when MainWindow singleton changes are merged

* Revert "REVERT ME when MainWindow singleton changes are merged"

This reverts commit 2de5520117b9aefb8eeb161d493de7cb275f7a5b.

src/main/app/config.test.js

@@ -44,6 +44,7 @@ jest.mock('main/badge', () => ({
 jest.mock('main/tray/tray', () => ({
     refreshTrayImages: jest.fn(),
 }));
+jest.mock('main/views/loadingScreen', () => ({}));
 jest.mock('main/windows/windowManager', () => ({
     handleUpdateConfig: jest.fn(),
     sendToRenderer: jest.fn(),

src/main/app/config.ts

@@ -12,6 +12,7 @@ import Config from 'common/config';
 import AutoLauncher from 'main/AutoLauncher';
 import {setUnreadBadgeSetting} from 'main/badge';
 import {refreshTrayImages} from 'main/tray/tray';
+import LoadingScreen from 'main/views/loadingScreen';
 import WindowManager from 'main/windows/windowManager';
 
 import {handleMainWindowIsShown} from './intercom';
@@ -80,7 +81,7 @@ export function handleDarkModeChange(darkMode: boolean) {
 
     refreshTrayImages(Config.trayIconTheme);
     WindowManager.sendToRenderer(DARK_MODE_CHANGE, darkMode);
-    WindowManager.updateLoadingScreenDarkMode(darkMode);
+    LoadingScreen.setDarkMode(darkMode);
 
     ipcMain.emit(EMIT_CONFIGURATION, true, Config.data);
 }