Fix mainWindow state not managed properly
Fix mainWindow state not managed properly

Need to call manage `mainWindowState.manage(mainWindow)` immediately instead of at the end of `createMainWindow()`, if not certain changes such as maximizing the main window before it has been registered will not be saved.

faceair/nativefier-slack,pixel9/nativefier,skewedlines/Nativefier,jiahaog/Nativefier,skewedlines/Nativefier,zucher/nativefier,zucher/nativefier,jiahaog/Nativefier,jiahaog/Nativefier,pixel9/nativefier,pixel9/nativefier,zucher/nativefier,gfpacheco/Nativefier,gfpacheco/Nativefier,skewedlines/Nativefier,faceair/nativefier-slack,gfpacheco/Nativefier