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
```

Beginne mit dem vorgeschlagenen Python AllureSeleniumPlugin-Beispiel und seinem capture_page_screenshot-Einstiegspunkt. Prüfe, wie die Robot Framework Library-Einstellung plugins=AllureSeleniumPlugin übergibt, und bestimme dann den erforderlichen Umfang der Integration. Done sollte ein nutzbares SeleniumLibrary-Plugin bereitstellen, das aufgenommene Seitenscreenshots an Allure-Berichte anhängt.

Vom Indexierungsmodell aus dem Issue-Text verfasst.