### 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)

}
				if (is_token_precision(tk.type)) {
					precision = get_token_precision(tk.type);
					tk = _get_token();
#ifdef DEBUG_ENABLED
					if (keyword_completion_context & CF_INTERPOLATION_QUALIFIER) {
						keyword_completion_context ^= CF_INTERPOLATION_QUALIFIER;
					}
					if (keyword_completion_context & CF_PRECISION_MODIFIER) {
						keyword_completion_context ^= CF_PRECISION_MODIFIER;
					}
					if (_lookup_next(next)) {
						if (is_token_datatype(next.type)) {
							keyword_completion_context = CF_UNSPECIFIED;
						}
					}
#endif 
				}
				if (shader->structs.has(tk.text)) {
					if (is_uniform) {
						_set_error(vformat(RTR("The '%s' data type is not supported for uniforms."), "struct"));
						return ERR_PARSE_ERROR;
					} else {
						_set_error(vformat(RTR("The '%s' data type not allowed here."), "struct"));
						return ERR_PARSE_ERROR;
					}
				}
				if (!is_token_datatype(tk.type)) {
					_set_error(RTR("Expected data type."));
					return ERR_PARSE_ERROR;