winewayland.drv: Bind to wl_compositor interface in the per-process instance.

In the following commits we'll introduce an internal swapchain in order
to support Vulkan cross-process rendering. In order to do that, we'll
need to create wl_surface objects from the per-process instance. So bind
to wl_compositor on the per-process instance as well.

Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>