[Translation] added LoggableTranslator.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #3015, #2435
| License       | MIT
| Doc PR       | symfony/symfony-docs/pull/4050
@Tobion $translator must implements TranslatorInterface and TranslatorBagInterface and I don't find the standard way to document it ?

```
/**
 * @param TranslatorInterface|TranslatorBagInterface $translator
 */
```