Include the passkey icon in the CDA QR code

[timcappalli]

To help associate the cross-device authentication flow with passkeys for users, it's important to show the passkey icon in the QR code.

The icon files can be found here:

• https://fidoalliance.org/wp-content/uploads/2024/01/FIDO_Passkey_mark_A.zip
• https://fidoalliance.org/wp-content/uploads/2024/01/FIDO_Passkey_mark_B_box.zip

[iinuwa]

Thanks, Tim!

To the implementor, since we're not adjusting to system dark/light scheme, FIDO_Passkey_mark_B_white.svg from the link above should work fine.

I believe we can wrap the QR code image in an Overlay widget, and center the passkey icon by setting the halign and valign properties to center.