feat: bar 点击回调添加按键和修饰键参数

on_click 新增 modifiers/button，使 bar item 可按按键与修饰键区分动作；
因参数增多，回调与 bar_click 改用结构参数封装。同时将 button_t 与
modifier 类型提升至公开头 include/zdwm/types.h 以供使用

src/bar/workspaces.c

@@ -143,13 +143,10 @@ static void bar_workspaces_update(
   data->dirty = false;
 }
 
-static zdwm_action_t bar_workspace_on_click(
-  zdwm_bar_item_t *item,
-  size_t cell_index,
-  int32_t x,
-  void *state
-) {
-  auto data = (bar_workspace_state_t *)state;
+static zdwm_action_t bar_workspace_on_click(zdwm_bar_click_params_t *params) {
+  auto cell_index = params->cell_index;
+  auto data       = (bar_workspace_state_t *)params->state;
+
   if (cell_index == data->count) {
     return (zdwm_action_t){
       .type            = ZDWM_ACTION_LAYOUT_CYCLE,