Fix part of 3550

Explanation

After many attempts, I could not figure out why the learner views, creator views, and collection view have duplicate NG_TRANSLATE_LANG_KEY cookies. I believe it has something to do with the path. One interesting observation is that if you console.log the cookie inside the top nav directive, and then console.log cookie after a timeout of 100ms, you see that the duplicate cookie is being set from somewhere else, but I just can't find where this happens.

I find that when I try to remove the cookies manually before doing the translation check, this actually makes the exploration view, collection view translations work properly, but this breaks the library, about, donate, etc. pages. One dirty fix would be to specify when to manually remove the duplicate cookie on each page, but it would be much better to find the root cause.

Anyways, this PR moves the translation check from the footer to the header, as the header is on every page whereas the footer isn't. As such, pages without a footer weren't capturing the language changes. The problem should now be localized to the case when a guest changes from the library to collection or exploration view.

Checklist

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