cursor-shape-v1: new protocol

This is based on the Chromium protocol [1].

[1]: https://chromium.googlesource.com/chromium/src/+/main/third_party/wayland-protocols/unstable/cursor-shapes/cursor-shapes-unstable-v1.xml



Signed-off-by: Simon Ser <contact@emersion.fr>
Closes: wayland/wayland-protocols#58
References: wayland/wayland-protocols!21