GPU invert node

[Firestar99]

Code below shows how much I had to change the gpu invert node. Most of the changes are due to not wanting to depend on gcore, as it currently doesn't compile for no_std. I think we could probably get away without changing it at all.

Graphite/node-graph/gcore-shader/src/gpu_invert.rs

Lines 4 to 23 in bf26734

	// #[node_macro::node(category("Raster: Adjustment"))]
	fn invert_copy(
	// _: impl Ctx,
	// #[implementations(
	// Color,
	// ImageFrameTable<Color>,
	// GradientStops,
	// )]
	// mut input: T,
	color: Color,
	) -> Color {
	// input.adjust(|color| {
	let color = color.to_gamma_srgb();
	let color = color.map_rgb(|c| color.a() - c);
	color.to_linear_srgb()
	// });
	// input
	}

The rust-gpu shader calling it:

Graphite/node-graph/gcore-shader/src/gpu_invert.rs

Lines 33 to 38 in bf26734

	#[spirv(fragment)]
	pub fn gpu_invert_fragment(#[spirv(frag_coord)] frag_coord: Vec4, #[spirv(descriptor_set = 0, binding = 0)] texture: &Image2d, color_out: &mut Vec4) {
	let color = Color::from(texture.fetch_with(frag_coord.xy().as_uvec2(), lod(0)));
	let color = invert_copy(color);
	*color_out = Vec4::from(color);
	}

[Firestar99]

The linker is erroring due to the wasm-specific flags somehow ending up in a native compile, probably env leaking again. Doesn't trigger locally, likely due to me using the mold linker. Will play around with it a bit more tomorrow.