Introduce CanvasMaterial

assets/canvas_shader.wgsl

@@ -0,0 +1,12 @@
+struct VertexOutput {
+    @builtin(position) clip_position: vec4<f32>,
+    @location(0) world_position: vec4<f32>,
+    @location(1) world_normal: vec3<f32>,
+    @location(2) uv: vec2<f32>,
+};
+
+@fragment
+fn fragment(input: VertexOutput) -> @location(0) vec4<f32> {
+    var output_color = vec4<f32>(input.uv, 1.0, 1.0);
+    return output_color;
+}