Add strip_workspace_name

See the issue #3163 (https://github.com/i3/i3/issues/3163).

Add strip_workspace_name to strip off the workspace name.

src/ipc.c

@@ -709,6 +709,9 @@ static void dump_bar_config(yajl_gen gen, Barconfig *config) {
     ystr("strip_workspace_numbers");
     y(bool, config->strip_workspace_numbers);
 
+    ystr("strip_workspace_name");
+    y(bool, config->strip_workspace_name);
+
     ystr("binding_mode_indicator");
     y(bool, !config->hide_binding_mode_indicator);