Users are required to override the Icon settings for iOS and manually set all icons for iOS. Since the App Store icon is required, it should be set by default, otherwise, users always have to override all icons and there would be no use of the Default Icon

Steps:
1. Create a new project
2. Project Settings > Default Icon > select any icon
3. Project Settings > iOS > Icon > App Store icons

Expected behavior: icon for App Store is set.
Actual behavior: no icon for App Store - users are required to manually override it (and all other iOS icons).

Reproduced with: 2017.3.0b1, 2017.2.0f2, 2017.1.1p3, 5.6.3p4.
Not reproduced with: 5.5.4p5 (no App Store icon in this version).