[Spike] Prepare multilingual setup

[kontent-ai]

[Spike] Prepare multilingual setup

[Chleba]

Some points of interest about a multi-languages solution:

• hold language option in cookie or LocalStorage
• switch language with URL (anchor or part of URL (/{lang}/page)
• check default URL when language is not part of URL in 404-page view with the script that will get default language from LocalStorage or cookies then redirect to the right page
• static text will be stored in JSON files in a key-value storage object
• dynamic text from Kontent

[IvanKiral]

Spike Result

The are created two versions for the spike project which uses two different libraries:
react-intl: https://github.com/IvanKiral/routing-react
react-i18n: https://github.com/IvanKiral/routing-react/tree/react-i18-next

We have decided to go with react-intl due to used workaround in react-i18n in multilangue routing.
The json files will have the flat format - means no nested objects (only key:value).
To use custom datetime formatting: https://formatjs.io/docs/react-intl/components/#formatteddateparts
It has the BSD-3-clause project must include:

• The full text of the license
• The original copyright notice

[Simply007]

Looks good!

We need to think about a full copy of the license in #206