ConstCreates a string for use with the
querySelector API
that selects this directive's attribute set to the given attributeValue.
import {html, selectTestId} from 'element-vir';
import {testWeb} from '@augment-vir/test';
import {assert} from '@augment-vir/assert';
const instance = testWeb.render(html`
<${MyElement}></${MyElement}>
`);
assert.instanceOf(instance, MyElement);
instance.shadowRoot.querySelector(selectTestId('my-test'));
Construct an attribute selector for the given test id.