[Feature] Add custom description to assertThat and/or Locator naming

With assertJ, we can add a custom name for given asserted object, for example:

Assertions.assertThat(mansion.guests()).as("Living Guests").isEqualTo(7);

Will result in:

[Living Guests] expected:<[7]> but was<[6]>

Selenide comes with element-aliasing as well as the .because() call (that does the similar thing, but not on asserted element, but the assertion itself):

$("div >> span").as("Living Guests").shouldHaveSize(7).because("The guest count should be valid")

The playwright-java assertions would be more readable if we'd be able to do similar thing with PlaywrightAssertions.assertThat or even the Locator/Page/ApiResponse itself, e.g.:

// on assertion:
PlaywrightAssertions.assertThat(questCount).hasText("7").because("The guest count should be valid");
// on asserted object:
PlaywrightAssertions.assertThat(questCount).as("Living Guests").hasText("7");
// on Locator
Locator guestCount = page.locator("div >> span").as("Living Guests");

Comienza leyendo la API PlaywrightAssertions y los tipos Locator, Page y ApiResponse mencionados en el issue. Compara los ejemplos de nombres solicitados a nivel de aserción y a nivel de objeto, y después define un enfoque compatible y coherente cuyos mensajes de error incluyan la descripción o el nombre personalizados.