### 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 changed = false;
	bool warnings_enabled = GLOBAL_GET("debug/shader_language/warnings/enable").booleanize();
	if (warnings_enabled != saved_warnings_enabled) {
		saved_warnings_enabled = warnings_enabled;
		changed = true;
	}
	bool treat_warning_as_errors = GLOBAL_GET("debug/shader_language/warnings/treat_warnings_as_errors").booleanize();
	if (treat_warning_as_errors != saved_treat_warning_as_errors) {
		saved_treat_warning_as_errors = treat_warning_as_errors;
		changed = true;
	}
	bool update_flags = false;
	for (int i = 0; i < ShaderWarning::WARNING_MAX; i++) {
		ShaderWarning::Code code = (ShaderWarning::Code)i;
		bool value = GLOBAL_GET("debug/shader_language/warnings/" + ShaderWarning::get_name_from_code(code).to_lower());
		if (saved_warnings[code] != value) {
			saved_warnings[code] = value;
			update_flags = true;
			changed = true;
		}
	}
	if (update_flags) {
		saved_warning_flags = (uint32_t)ShaderWarning::get_flags_from_codemap(saved_warnings);
	}
	if (p_validate && changed && shader_editor && shader_editor->get_edited_shader().is_valid()) {
		shader_editor->validate_script();
	}
}
void TextShaderEditor::_check_for_external_edit() {