Dynamic Icon for Onboarding UI

[jacob-benedict]

Is your feature request related to a problem? Please describe.
When using the onboarding ui, it only uses the default icon.

Describe the solution you'd like
The option to specify the icon used as part of the payload.

Describe alternatives you've considered
In my particular use case, changing the default icon was enough, but I could imagine use cases where the ability to alter the icon would be useful.