Add RowHeight, RowSpacing and Orientation properties to RadioButtonGroup

RadioButtonGroup rows cannot be compacted or laid out horizontally. On both desktop and web the row height is a fixed constant (32px desktop, 28px web) with a fixed 4px gap, so groups always render at the same generous row pitch — reducing the font size makes the text smaller but does not move the rows closer together, because the row height does not depend on the font.

Add three layout properties to RadioButtonGroup:

Property Type Default Meaning RowHeight Integer 0 = automatic Height of each radio row. 0 keeps the platform default; positive values make rows tighter or taller. RowSpacing Integer 4 Gap between rows along the layout direction, so it also spaces buttons horizontally. Orientation Orientation Vertical Orientation.Horizontal lays the buttons out in a single row across the control.

All three default to today's appearance, so existing projects are unchanged. For example, RowHeight = 22 with RowSpacing = 2 compacts the row pitch from 36px to 24px on desktop.

Requested on the forum: https://forum.objo.dev/d/1361-radiobuttongroup-suggestions