Adding support for iPhone 6 Plus icons

- For App icon, 180x180: Added new `-60@3x.png`
- For Spotlight search results icon, 120x120: Verified it uses existing `-60@2x.png`
- For Settings icon, 87x87: Added new `-Small@3x.png`
Merge pull request #6043 from FokkeZB/patch-1

Adding support for iPhone 6 Plus icons