fix: add contentForLanguage resolver for nav item content

[dancastellon]

Resolves #4912
Impact: minor
Type: bugfix

Issue

The NavigationItemData.content resolver currently filters down the content array by the language argument provided to the navigationTreeById GraphQL query. Instead, it should return the array without filtering for the operator UI, and have a separate resolver that storefront can use to load the translated content string.

Solution

This PR removes the filtering from the content resolver and adds a contentForLanguage resolver that returns the content string in the correct language. If a translation for that language is not available, it defaults to the first content provided.

Breaking changes

None

Testing

1. Edit a navigation item in the database. Under draftData and data, add a translation to the array:

{
  "language" : "es",
  "value" : "Camisas"
}

2. Run this query in Graphiql:

{
  primaryShop {
    defaultNavigationTree(language: "es") {
      items {
        navigationItem {
          data {
          	content {
              value
            }
            contentForLanguage
            classNames
            url
            isUrlRelative
            shouldOpenInNewWindow
        	}
          draftData {
          	content {
              value
            }
            contentForLanguage
            classNames
            url
            isUrlRelative
            shouldOpenInNewWindow
        	}
        }
      }
    }
  }
}

3. Confirm contentForLanguage returns the Spanish content.

[kieckhafer]

👍 This provides the translation (if available), or the default english if no translation is available, on the contentForLangauage prop.

The failing test is a timeout issue that we've seen across other branches, and shouldn't block this particular PR.