### Godot version

Godot 4.0.3

### System information

Windows 10 64 bits NVIDIA GeForce GTX 1060

### Issue description

Ctrl+K is a shortcut normally used to comment out the current line. It works in the shader editor, but for some reason, it doesn't if your shader has the `.gdshaderinc` extension (aka it's a shader include). Shader Includes are the same language, we should be able to use that feature.

### Steps to reproduce

Create a `.gdshaderinc` file. Write some code in it. Observe you can't use Ctrl+K to comment out lines.

### Minimal reproduction project

[CommentLinesShaderInc.zip](https://github.com/godotengine/godot/files/11739881/CommentLinesShaderInc.zip)

_complete_include_paths_search(EditorFileSystem::get_singleton()->get_filesystem(), r_options);
}
void ShaderTextEditor::_code_complete_script(const String &p_code, List<ScriptLanguage::CodeCompletionOption> *r_options) {
	List<ScriptLanguage::CodeCompletionOption> pp_options;
	List<ScriptLanguage::CodeCompletionOption> pp_defines;
	ShaderPreprocessor preprocessor;
	String code;
	String resource_path = (shader.is_valid() ? shader->get_path() : shader_inc->get_path());
	complete_from_path = resource_path.get_base_dir();
	if (!complete_from_path.ends_with("/")) {
		complete_from_path += "/";
	}
	preprocessor.preprocess(p_code, resource_path, code, nullptr, nullptr, nullptr, nullptr, &pp_options, &pp_defines, _complete_include_paths);
	complete_from_path = String();
	if (pp_options.size()) {
		for (const ScriptLanguage::CodeCompletionOption &E : pp_options) {