feat(client): store bar_id argument

include/client.hpp

@@ -29,6 +29,7 @@ class Client {
   struct zwp_idle_inhibit_manager_v1 *idle_inhibit_manager = nullptr;
   std::vector<std::unique_ptr<Bar>>   bars;
   Config                              config;
+  std::string                         bar_id;
 
  private:
   Client() = default;

src/client.cpp

@@ -199,7 +199,6 @@ int waybar::Client::main(int argc, char *argv[]) {
   bool        show_version = false;
   std::string config_opt;
   std::string style_opt;
-  std::string bar_id;
   std::string log_level;
   auto        cli = clara::detail::Help(show_help) |
              clara::detail::Opt(show_version)["-v"]["--version"]("Show version") |