Vertical layout for segmented buttons, and cosmic example improvements

[mmstick]

• Adds Orientation enum for defining the vertical or horizontal layout of a widget.
• Implements vertical orientation for the segmented button widget and its cosmic styles.
• cosmic pages now have their own states and messages, and all controls are now mapped to unique states

[13r0ck]

Hector prefers duplicate widgets rather then an orientation enum. Maybe we should split this to stay consistant with upstream?
iced-rs/iced#1596 (review)

[mmstick]

@13r0ck I'll try doing that then. GTK habits

[13r0ck]

lol no worries. Thank you!