### 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)

RS::GlobalShaderParameterType gvt = RS::get_singleton()->global_shader_parameter_get_type(p_variable);
	return (ShaderLanguage::DataType)RS::global_shader_uniform_type_get_shader_datatype(gvt);
}
static String complete_from_path;
static void _complete_include_paths_search(EditorFileSystemDirectory *p_efsd, List<ScriptLanguage::CodeCompletionOption> *r_options) {
	if (!p_efsd) {
		return;
	}
	for (int i = 0; i < p_efsd->get_file_count(); i++) {
		if (p_efsd->get_file_type(i) == SNAME("ShaderInclude")) {
			String path = p_efsd->get_file_path(i);
			if (path.begins_with(complete_from_path)) {
				path = path.replace_first(complete_from_path, "");
			}
			r_options->push_back(ScriptLanguage::CodeCompletionOption(path, ScriptLanguage::CODE_COMPLETION_KIND_FILE_PATH));
		}
	}
	for (int j = 0; j < p_efsd->get_subdir_count(); j++) {
		_complete_include_paths_search(p_efsd->get_subdir(j), r_options);
	}
}
static void _complete_include_paths(List<ScriptLanguage::CodeCompletionOption> *r_options) {