Localize the theme UI elements

[fflorent]

I see these elements are not localized (and are not proposed in GitLocalized).

The feedback box

The feedback box appears at the bottom of the page:

The website title

In the top-left corner, the website title is in English:

The top menu bar

In the top-right corner:

• "Back to Grist"
• "Community"
• "Search" (the placeholder in the text field)

The bottom-left corner

The quick links and "Edit on Github":

The help assistant

The popup named "Instant Answers" when clicking on the button in the bottom-right corner (would be neat if that could be translated, if possible, not sure how):