As a bilingual user, I want the language switcher button readily available, so that I don't have to scroll so much just to find the button to change languages.

Acceptance criteria

• Implement treatment of button and its placement, with sufficiently large tap target, as arrived at in T119658: [Design] Language button on footer.
• It works in ResourceLoader impaired and <noscript> UAs.
• It is possible to run this version in an A/B fashion.
• When in force sampled in Schema:MobileWebLanguageSwitcher logging should result in the button's tap having a languageButtonVersion distinct from the existing 'bottom-of-article' value.
• It has unit tests.
• It has ATDD tests.
• It works on localhost.
• it works on the beta cluster in both beta mode (100%) and by default (10%).
• it is deployed at 100% in beta on the prod cluster.