hello, how to obtain "key" need to be sent into zwp_virtual_keyboard_v1_key? Here is an example from X11 world: 
```
keysym = (unsigned int)XStringToKeysym("BackSpace"); // 0xFF08
keycode = XKeysymToKeycode(display, keysym); // 22
XTestFakeKeyEvent(display, keycode, is_press, CurrentTime);
```
In Wayland you can use:
```
xkb_keysym_t keysym = xkb_keysym_from_name("BackSpace", XKB_KEYSYM_NO_FLAGS); // 0xFF08
```
but it's not clear what should be passed to zwp_virtual_keyboard_v1_key (22? but how to get 22 from 0xFF08 in Wayland?)