Swapped scrollable for cosmic::scrollable

- Renamed scrollbar to scrollable

src/widget/scrollable.rs

@@ -0,0 +1,8 @@
+#[macro_export]
+macro_rules! scrollable {
+    ($x:expr) => (
+        $crate::iced::widget::scrollable($x)
+            .scrollbar_width(8)
+            .scroller_width(8)
+    );
+}