### Godot version

4.0.2.stable

### System information

Windows 11, Vulkan, RTX2070 Super

### Issue description

Reading from `VIEWPORT_SIZE` in the `light()` function causes spatial shader to break and renders as default white.

### Steps to reproduce

![image](https://user-images.githubusercontent.com/20043270/236914345-ccd12e83-4431-4a53-b67b-028c8ef5719b.png)

when line 51 is present the fails to compile with the following message in the output log but no compilation errors.

```
servers/rendering/renderer_rd/forward_clustered/scene_shader_forward_clustered.cpp:171 - Condition "!shader_singleton->shader.version_is_valid(version)" is true.
  drivers/vulkan/rendering_device_vulkan.cpp:5361 - Condition "!shader" is true. Returning: RID()
  drivers/vulkan/rendering_device_vulkan.cpp:5835 - Condition "!us" is true.
```

commenting out line 51 solves this issue.

[The documentation](https://docs.godotengine.org/en/stable/tutorials/shaders/shader_reference/spatial_shader.html#light-built-ins) states that `VIEWPORT_SIZE` should be available to the `light()` function.

### Minimal reproduction project

N/A
RD::PolygonCullMode cull_mode_rd = cull_mode_rd_table[i][cull];
		for (int j = 0; j < RS::PRIMITIVE_MAX; j++) {
			RD::RenderPrimitive primitive_rd_table[RS::PRIMITIVE_MAX] = {
				RD::RENDER_PRIMITIVE_POINTS,
				RD::RENDER_PRIMITIVE_LINES,
				RD::RENDER_PRIMITIVE_LINESTRIPS,
				RD::RENDER_PRIMITIVE_TRIANGLES,
				RD::RENDER_PRIMITIVE_TRIANGLE_STRIPS,
			};
			RD::RenderPrimitive primitive_rd = uses_point_size ? RD::RENDER_PRIMITIVE_POINTS : primitive_rd_table[j];
			for (int k = 0; k < SHADER_VERSION_MAX; k++) {
				if (!static_cast<SceneShaderForwardMobile *>(singleton)->shader.is_variant_enabled(k)) {
					continue;
				}
				RD::PipelineRasterizationState raster_state;
				raster_state.cull_mode = cull_mode_rd;
				raster_state.wireframe = wireframe;
				RD::PipelineColorBlendState blend_state;
				RD::PipelineDepthStencilState depth_stencil = depth_stencil_state;
				RD::PipelineMultisampleState multisample_state;
				if (uses_alpha || uses_blend_alpha) {
					
					if (alpha_antialiasing_mode == ALPHA_ANTIALIASING_ALPHA_TO_COVERAGE) {
						multisample_state.enable_alpha_to_coverage = true;
					} else if (alpha_antialiasing_mode == ALPHA_ANTIALIASING_ALPHA_TO_COVERAGE_AND_TO_ONE) {
						multisample_state.enable_alpha_to_coverage = true;
						multisample_state.enable_alpha_to_one = true;
					}
					if (k == SHADER_VERSION_COLOR_PASS || k == SHADER_VERSION_COLOR_PASS_MULTIVIEW || k == SHADER_VERSION_LIGHTMAP_COLOR_PASS || k == SHADER_VERSION_LIGHTMAP_COLOR_PASS_MULTIVIEW) {
						blend_state = blend_state_blend;