[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");

まず PlaywrightAssertions API と、issue で参照されている Locator、Page、ApiResponse 型を読みます。アサーションレベルとオブジェクトレベルで要求されている命名例を比較し、その後、失敗メッセージにカスタムの説明または名前を含める、一貫したサポート対象のアプローチを定義します。