### Godot version

4.0.beta16

### System information

Windows 10 Pro x64, GLES3, RTX 3080 Ti (528.02)

### Issue description

In Compatibility/GLES3 back-end, shaders which use a uniform to get the normal roughness buffer cannot compile. For example, the shader:
```glsl
shader_type spatial;

uniform sampler2D normal_roughness_texture : hint_normal_roughness_texture;

void fragment() {
    vec4 sample = texture(normal_roughness_texture, UV);
}
```
results in an error in the output:
```
  drivers/gles3/shader_gles3.cpp:242 - SceneShaderGLES3: Fragment shader compilation failed:
  0(890) : error C1503: undefined variable "normal_roughness_buffer"
  
  drivers/gles3/shader_gles3.cpp:342 - Method/function failed.
```

If I switch over to the Mobile or Forward+ backends, there is no shader compilation error.

### Steps to reproduce

Open the attached reproduction in the 4.0.beta16 editor.

When the scene is opened, the error is produced automatically:
1. Open `scene.tscn`
2. Open Output to review error

When the scene is saved with any changes made to the shader, the same error is also produced:
1. Open `scene.tscn`
2. Open `example.gdshader` in the shader editor.
3. Make a compile-able change to the shader.
4. Save the scene
5. Open Output to review the error

### Minimal reproduction project

[NormalRoughnessTexture_GLES3_Error.zip](https://github.com/godotengine/godot/files/10534253/NormalRoughnessTexture_GLES3_Error.zip)

}
				}
			} break;
			case TK_STRUCT: {
				ShaderNode::Struct st;
				DataType type;
#ifdef DEBUG_ENABLED
				keyword_completion_context = CF_UNSPECIFIED;
#endif 
				tk = _get_token();
				if (tk.type == TK_IDENTIFIER) {
					st.name = tk.text;
					if (shader->constants.has(st.name) || shader->structs.has(st.name)) {
						_set_redefinition_error(String(st.name));
						return ERR_PARSE_ERROR;
					}
					tk = _get_token();
					if (tk.type != TK_CURLY_BRACKET_OPEN) {
						_set_expected_error("{");
						return ERR_PARSE_ERROR;
					}
				} else {
					_set_error(RTR("Expected a struct identifier."));
					return ERR_PARSE_ERROR;
				}
				StructNode *st_node = alloc_node<StructNode>();
				st.shader_struct = st_node;
				int member_count = 0;
				HashSet<String> member_names;
				while (true) {