Banner on about:tor page

We should add a banner on Tor Browser's about:tor page that links to the crowdfunding donation page. This will make most users aware of the crowdfunding campaign when Tor Browser updates next.

It might be fun and helpful to users to make it look stylistically similar to the crowdfunding page. Ideally we would translate the banner to several languages.

The next Tor Browser release is December 15, so we should aim for then at the very latest.