Convert macros footnote and display-footnotes to footnote and putFootnotes

Actually, we can't do this easily.

• footnotes in XWiki are necessarily inline. In Confluence, they can be block. So we can't really migrate to footnote directly. Handling this would require making our footnote macro support block content.
• In Confluence, they are inside a div with class content-wrapper, and the content which is before the footnote is in a dedicated paragraph. I suppose the content following the footnote would also be in a dedicated paragraph. Migrating this would lead to a footnote reference being on its own line

Here's how it looks:

<div class="content-wrapper">
    <p>What follows is a footnote</p>
    <ac:structured-macro ac:name="footnote" ac:schema-version="1" ac:macro-id="2d786bbc-18e4-4a80-8a6a-ba734bbb7b99">
        <ac:parameter ac:name="atlassian-macro-output-type">INLINE</ac:parameter>
        <ac:rich-text-body>
            <p>The content of the footnote</p>
        </ac:rich-text-body>
    </ac:structured-macro>
</div>