allure plugin for robotframework-seleniumlibrary

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This could be an good example or part of a robot adapter
```python
import allure
from SeleniumLibrary import ScreenshotKeywords
from SeleniumLibrary.base import keyword, LibraryComponent

class AllureSeleniumPlugin(LibraryComponent):

@keyword
def capture_page_screenshot(self, filename='selenium-screenshot-{index}.png'):
path = ScreenshotKeywords(ctx=self.ctx).capture_page_screenshot(filename)
allure.attach.file(path, attachment_type=allure.attachment_type.PNG)
```

```robot
Library SeleniumLibrary plugins=AllureSeleniumPlugin
```

Comienza con el ejemplo propuesto de Python AllureSeleniumPlugin y su punto de entrada capture_page_screenshot. Comprueba cómo la configuración de Robot Framework Library pasa plugins=AllureSeleniumPlugin y, a continuación, determina el alcance requerido de la integración. Done debe proporcionar un plugin utilizable de SeleniumLibrary que adjunte las capturas de pantalla de las páginas capturadas a los informes de Allure.

Escrito por el modelo de indexación a partir del texto del issue.