adds fix to respect translation for header and nav blocks

[markconroy]

Closes #144

[ekes]

You know during drop-in I was trying to remember what the one-line way of getting the translated entity was, but just couldn't remember:

EntityRepositoryInterface::getTranslationFromContext

There are a few reasons to use this in preference to getting the current language and requesting the translation:

• The EntityRepository service uses the fallback language settings to get the most appropriate translation;
• Additionally the service is designed to default to the interface language, adds some appropriate cache tags;
• Getting the entity translation, on the other hand, makes a clone of the original default language if the translation doesn't exist. So this is more useful if you are wanting to create, or update, a translation of an entity.

So using \Drupal::service('entity.repository')->getTranslationFromContext($entity), or the appropriate equivalent having loaded entity.repository by dependency injection, would seem to be the better way of getting the desired translation.

[ekes]

Just 9.4 failing. Should be removed from test matrix.

@markconroy I've just written the code, not tested it, do you want to check this still works for your site?
@stephen-cox Do you want to do an eye code check?

Then we could merge?

[finnlewis]

@markconroy could you check this still does what it should?

[finnlewis]

Closing this in favour of #157