### 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
actions.render_mode_values["blend_sub"] = Pair<int *, int>(&blend_mode, BLEND_MODE_SUB);
	actions.render_mode_values["blend_mul"] = Pair<int *, int>(&blend_mode, BLEND_MODE_MUL);
	actions.render_mode_values["alpha_to_coverage"] = Pair<int *, int>(&alpha_antialiasing_mode, ALPHA_ANTIALIASING_ALPHA_TO_COVERAGE);
	actions.render_mode_values["alpha_to_coverage_and_one"] = Pair<int *, int>(&alpha_antialiasing_mode, ALPHA_ANTIALIASING_ALPHA_TO_COVERAGE_AND_TO_ONE);
	actions.render_mode_values["depth_draw_never"] = Pair<int *, int>(&depth_drawi, DEPTH_DRAW_DISABLED);
	actions.render_mode_values["depth_draw_opaque"] = Pair<int *, int>(&depth_drawi, DEPTH_DRAW_OPAQUE);
	actions.render_mode_values["depth_draw_always"] = Pair<int *, int>(&depth_drawi, DEPTH_DRAW_ALWAYS);
	actions.render_mode_values["depth_test_disabled"] = Pair<int *, int>(&depth_testi, DEPTH_TEST_DISABLED);
	actions.render_mode_values["cull_disabled"] = Pair<int *, int>(&cull, CULL_DISABLED);
	actions.render_mode_values["cull_front"] = Pair<int *, int>(&cull, CULL_FRONT);
	actions.render_mode_values["cull_back"] = Pair<int *, int>(&cull, CULL_BACK);
	actions.render_mode_flags["unshaded"] = &unshaded;
	actions.render_mode_flags["wireframe"] = &wireframe;
	actions.render_mode_flags["particle_trails"] = &uses_particle_trails;
	actions.usage_flag_pointers["ALPHA"] = &uses_alpha;
	actions.usage_flag_pointers["ALPHA_SCISSOR_THRESHOLD"] = &uses_alpha_clip;
	actions.usage_flag_pointers["ALPHA_HASH_SCALE"] = &uses_alpha_clip;
	actions.usage_flag_pointers["ALPHA_ANTIALIASING_EDGE"] = &uses_alpha_antialiasing;
	actions.usage_flag_pointers["ALPHA_TEXTURE_COORDINATE"] = &uses_alpha_antialiasing;
	actions.render_mode_flags["depth_prepass_alpha"] = &uses_depth_prepass_alpha;
	actions.usage_flag_pointers["SSS_STRENGTH"] = &uses_sss;
	actions.usage_flag_pointers["SSS_TRANSMITTANCE_DEPTH"] = &uses_transmittance;
	actions.usage_flag_pointers["DISCARD"] = &uses_discard;
	actions.usage_flag_pointers["TIME"] = &uses_time;
	actions.usage_flag_pointers["ROUGHNESS"] = &uses_roughness;
	actions.usage_flag_pointers["NORMAL"] = &uses_normal;
	actions.usage_flag_pointers["NORMAL_MAP"] = &uses_normal;
	actions.usage_flag_pointers["POINT_SIZE"] = &uses_point_size;
	actions.usage_flag_pointers["POINT_COORD"] = &uses_point_size;
	actions.write_flag_pointers["MODELVIEW_MATRIX"] = &writes_modelview_or_projection;