fix(tab): focus largest pane instead of topmost

When multiple Panes have the same x coord in a MoveTabOrFocus event that switches tabs, instead of picking the pane at the top to focus, choose the one biggest one. This ensures that in stacked layouts, the focused pane is opened again when moving, instead of always focusing the top pane.

closes #3006

zellij-server/src/panes/tiled_panes/tiled_pane_grid.rs

@@ -1039,14 +1039,14 @@ impl<'a> TiledPaneGrid<'a> {
                 Direction::Left => {
                     let x_comparison = a.x().cmp(&b.x());
                     match x_comparison {
-                        Ordering::Equal => b.y().cmp(&a.y()),
+                        Ordering::Equal => a.rows().cmp(&b.rows()).then(b.y().cmp(&a.y())),
                         _ => x_comparison,
                     }
                 },
                 Direction::Right => {
                     let x_comparison = b.x().cmp(&a.x());
                     match x_comparison {
-                        Ordering::Equal => b.y().cmp(&a.y()),
+                        Ordering::Equal => a.rows().cmp(&b.rows()).then(b.y().cmp(&a.y())),
                         _ => x_comparison,
                     }
                 },