Changing icons of demo app

[etoledom]

Description

Proposing different icons for the demo app:

The idea is that they represent the skeleton of a Gravatar card, using the color schemes of UIKit and SwiftUI.

Testing Steps

[andrewdmontgomery]

I love that for SwiftUI, since SwiftUI uses the Blue/Black color palette. Can we use the Orange/White palette (of Swift) for UIKit?

The main reason for me is here:

I know Gravatar's color is blue. But the G icon within the App Icon conveys "this is Gravatar" very well. We can use color to differentiate the important difference.

[etoledom]

@andrewdmontgomery - @pinarol - Updated!