[11.x] Allow TestComponent to be macroable

[ziadoz]

This PR allows the TestComponent class to be macroable like TestView.

In my case, I'd like to be able to chain on my own custom HTML assertion methods:

TestComponent::macro('assertElement', fn (): => //...);

public function test_my_component(): void
{
    $this->component(MyComponent::class, [...])->assertElement(...);
}