Update to work done on T418770: Onboarding: Interests Selection

Background

When users have multiple languages installed on the app, it's unclear during onboarding if selections will apply to all languages or just the primary. It's also confusing because you can search for articles across different languages and add them to your interests, but the ones that come up through the topic search and topic selection are only in your primary language. The behavior is that topics work across languages automatically, but articles do not.

User Story

As a user of the Wikipedia app in English and Spanish equally, I would like to select articles within my other language, so that I can set up both of my feeds quickly and easily and receive recommendations for my reading across both languages.

Requirements

• [Already in place] When a user selects a topic that should be language agnostic, users should be able to receive recommendations in all languages.
• [Already in place] When a user searches for an article: they should be able to add an article from a different language
• Add a language drop-down selector to the onboarding screen so that users can easily change what language they're doing the Topic search within
  • Upon changing the drop down: topics stay consistent (keep existing topic selections)
  • Articles shown under topics update to selected language (keep existing article selections)

Design Link

TBA