Support _ui-culture for Anonymous SmartForms

Runtime translations for Anonymous SmartForms currently rely on the browser’s preferred language. The _ui-culture parameter, which allows the UI culture to be explicitly specified for authenticated users, does not currently work for anonymous users.

We would like to have a supported mechanism, such as _ui-culture, to explicitly define the UI culture for Anonymous SmartForms. This would enable public-facing forms to support language selection or language switching without requiring users to change their browser language settings.

The current workaround is to create a separate form for each language and direct users to the appropriate form via the URL, which increases development and maintenance effort. Supporting explicit UI culture selection for anonymous users would provide a more flexible and maintainable approach for multilingual public-facing forms.