### 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)

bool use_autoreload = bool(EDITOR_GET("text_editor/behavior/files/auto_reload_scripts_on_external_change"));
	if (shader_inc.is_valid()) {
		if (shader_inc->get_last_modified_time() != FileAccess::get_modified_time(shader_inc->get_path())) {
			if (use_autoreload) {
				_reload_shader_include_from_disk();
			} else {
				disk_changed->call_deferred(SNAME("popup_centered"));
			}
		}
		return;
	}
	if (shader.is_null() || shader->is_built_in()) {
		return;
	}
	if (shader->get_last_modified_time() != FileAccess::get_modified_time(shader->get_path())) {
		if (use_autoreload) {
			_reload_shader_from_disk();
		} else {
			disk_changed->call_deferred(SNAME("popup_centered"));
		}
	}
}
void TextShaderEditor::_reload_shader_from_disk() {