Mouse button handling

src/Game.zig

@@ -864,6 +864,18 @@ pub fn onMouseMove(self: *Game, dx: f32, dy: f32) void {
     self.camera_yaw = @mod(self.camera_yaw, 2 * std.math.pi);
 }
 
+pub fn onMouseDown(self: *Game, button: glfw.MouseButton, mods: glfw.Mods) void {
+    _ = self;
+    _ = button;
+    _ = mods;
+}
+
+pub fn onMouseUp(self: *Game, button: glfw.MouseButton, mods: glfw.Mods) void {
+    _ = self;
+    _ = button;
+    _ = mods;
+}
+
 fn render(self: *Game) !void {
     const engine = self.engine;
     const extent = self.swapchain.extent;