add FavoriteIcon and use in fullscreen page

ui/widgets/favoriteicon.go

@@ -0,0 +1,27 @@
+package widgets
+
+import (
+	"github.com/dweymouth/supersonic/ui/theme"
+)
+
+type FavoriteIcon struct {
+	TappableIcon
+
+	Favorite bool
+}
+
+func NewFavoriteIcon() *FavoriteIcon {
+	f := &FavoriteIcon{}
+	f.Resource = theme.NotFavoriteIcon
+	f.ExtendBaseWidget(f)
+	return f
+}
+
+func (f *FavoriteIcon) Refresh() {
+	if f.Favorite {
+		f.Resource = theme.FavoriteIcon
+	} else {
+		f.Resource = theme.NotFavoriteIcon
+	}
+	f.BaseWidget.Refresh()
+}