And of course, gsk_render_node_get_name() is gone, too.
The replacement is of course debug nodes.
As a side effect, GskRenderNode is now *really* immutable.
This is a special case of the transform node that does a 2D translation.
The implementation in the Vulkan and GL renderers is crude and just does
the same as the transform node.
Nothing uses that node yet.
Add a setter for per-renderer debug flags, and use
them where possible. Some places don't have easy access
to a renderer, so this is not complete.
Also, use g_message instead of g_print throughout.
