A select for the viewer of one library (PhoenixKitPhotos.Viewer): "Default", "Swipe
viewer", "Classic viewer". It shows nothing to someone who may not choose
(Viewer.can_set?/2), and checks again when it saves.
Usage
<.live_component
module={PhoenixKitPhotos.Components.ViewerPicker}
id="viewer-picker"
library_uuid={library_uuid}
auth={scope}
/>When the choice is saved the parent LiveView gets {:viewer_changed, library_uuid} and
reads PhoenixKitPhotos.Viewer.for_library/1 again.