Browse icons widget

Thanks for the request, we already made an Icon Picker in Alpha3, you need to enable module 'Ui Icon Picker' and you can see how it works enabling 'Ui Icon Example' and going to Administration > Appearance > UI Icons Form Example.
For now it's not the default element, so not available directly in CKEditor or Field UI because I am not pleased with the JavaScript part and have concerns on the accessibility.

Will add an option to switch to the picker in CKeditor for beta1.

if we can make it a little bit more simple, just to list all icons, I think it will be easier for non tech savvy users.

So, without the settings form? If you define no settings in your icon pack definition, the settings form will not show up.

As for now this field is not planned for UI icons, if anyone want to create a dedicated modules, would review.