Sets or gets a site's current display language.
Setting the currentLanguage property changes a site's display language.
The current page is reloaded in the newly set language.
Set the current language using a two-letter language code. The code must
represent one of the languages set to show on a site.
You can retrieve a site's languages and corresponding language codes using
the siteLanguages property.
Getting the currentLanguage property gets the two-letter language code
of a site's current display language.