### 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)

} else {
		code = shader_inc->get_code();
	}
	ShaderPreprocessor preprocessor;
	String code_pp;
	String error_pp;
	List<ShaderPreprocessor::FilePosition> err_positions;
	List<ShaderPreprocessor::Region> regions;
	String filename;
	if (shader.is_valid()) {
		filename = shader->get_path();
	} else if (shader_inc.is_valid()) {
		filename = shader_inc->get_path();
	}
	last_compile_result = preprocessor.preprocess(code, filename, code_pp, &error_pp, &err_positions, &regions);
	for (int i = 0; i < get_text_editor()->get_line_count(); i++) {
		get_text_editor()->set_line_background_color(i, Color(0, 0, 0, 0));
	}
	syntax_highlighter->clear_disabled_branch_regions();
	for (const ShaderPreprocessor::Region &region : regions) {
		if (!region.enabled) {
			if (filename != region.file) {
				continue;
			}
			syntax_highlighter->add_disabled_branch_region(Point2i(region.from_line, region.to_line));
		}
	}
	set_error("");
	set_error_count(0);
	if (last_compile_result != OK) {