cleanup custom material

assets/shaders/custom_material.wgsl

@@ -1,11 +0,0 @@
-#import bevy_pbr::forward_io::VertexOutput
-
-@group(2) @binding(1) var material_color_texture: texture_2d<f32>;
-@group(2) @binding(2) var material_color_sampler: sampler;
-
-@fragment
-fn fragment(
-    mesh: VertexOutput,
-) -> @location(0) vec4<f32> {
-    return textureSample(material_color_texture, material_color_sampler, mesh.uv);
-}

assets/shaders/custom_material_import.wgsl

@@ -1,2 +0,0 @@
-// this is made available to the importing module
-const COLOR_MULTIPLIER: vec4<f32> = vec4<f32>(1.0, 1.0, 1.0, 0.5);