Draft: Add language switcher to JH footer

Related issue link: #923 (closed)

Related FE MR: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/102509

What does this MR do and why?

Add language switcher to JH footer.

jh/app/views/devise/shared/_footer.html.haml overrided upstream app/views/devise/shared/_language_switcher.html.haml,

so need to add render again in the JH template file.

Screenshots

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/cc EM @prajnamas