mod(container): support layout direction handling for child elements

src/zterm.zig

@@ -1,6 +1,14 @@
+const container = @import("container.zig");
+
 pub const App = @import("app.zig").App;
 pub const Renderer = @import("render.zig");
 
+// Container Configurations
+pub const Border = container.Border;
+pub const Rectangle = container.Rectangle;
+pub const Scroll = container.Scroll;
+pub const Layout = container.Layout;
+
 pub const Cell = @import("cell.zig");
 pub const Color = @import("color.zig").Color;
 pub const Key = @import("key.zig");