Get a BBB evergreen page

Returns one page from the evergreen library BBB keeps under https://www.bbb.org/all/ (tips, topic hubs such as tax or holiday advice, scam studies): its title, introduction, body text, links, main image and last-modified time. BBB folds older newsroom stories into these pages and redirects the old article URL, so the url can be either the evergreen page itself or an article URL that bbb-article reports as moved; requested_url, final_url and every redirect between them are returned. published_at is always present and is null, because BBB publishes no date for these pages: modified_at is when BBB last edited the page, not when a story it replaced was published, and the page may cover a wider topic than that story did. The original article ID is not on the page; article_id repeats the one in the requested article URL. Returns 404 when the page does not exist, when an article URL has not been moved (read it with bbb-article), and when BBB redirects the URL somewhere outside /all/; the error names the destination and the answer is permanent. Content BBB loads in the browser for the visitor's local BBB is not included.