Add 'i18nMetadata' and 'lang' properties to Interactive JSON

[#69671508]
Add flag images

[#69671508]

Generated using:
https://github.com/koppi/iso-country-flags-svg-collection
(MIT License)

PNGs look better than SVG when scaled to small size.
Add language select menu

[#69671508]
Add locales metadata and Polish translation of "Oil and Water"

[#69671508]
Do not setup language select menu when i18nMetadata isn't available

[#69671508]
Serialize 'lang' and 'i18nMetadata' properties

[#69671508]
Add missing CSS styles of the language icon

[#69671508]
Add Spanish translation of "Oil and Water" and update Polish one

[#69671508]