Since EUI is now providing controls that contain text (i.e. combo box), we need to think about how to allow for internationalisation. Cloud UI is already using react-intl heavily, but I don't think EUI should have any opinion over how the i18n is done.

I wondered if it might work to have an extra prop, e.g. translations, which is an object of all the required strings (or more precisely React nodes, to allow for custom formatting / content). The prop types would document the required keys and the default values.

cc @cjcenizal