Call all ewmh_update_* functions together when necessary

The testcase is changed because it was actually incorrect. Easy to
verify because:
> _NET_CURRENT_DESKTOP
> …
> The index of the current desktop. This is always an integer between 0
> and _NET_NUMBER_OF_DESKTOPS - 1.

Fixes #3696.
Also updates the viewports.

Finally, fixes an issue with _NET_CURRENT_DESKTOP not being updated
after a workspace rename. Example:
- workspaces 1, 2, 3
- rename workspace 1 to 5
- All workspaces changed their index but _NET_CURRENT_DESKTOP was not
updated

src/commands.c

@@ -2002,9 +2002,7 @@ void cmd_rename_workspace(I3_CMD, const char *old_name, const char *new_name) {
     cmd_output->needs_tree_render = true;
     ysuccess(true);
 
-    ewmh_update_desktop_names();
-    ewmh_update_desktop_viewport();
-    ewmh_update_current_desktop();
+    ewmh_update_desktop_properties();
 
     startup_sequence_rename_workspace(old_name_copy, new_name);
     free(old_name_copy);