[FEATURE] First version of the extension, javascript to make a frontend request and returning a json with page information

[RinyVT]

Frontend request

This is a new extension which handles frontend requests from within the backend, this was/is a functionality in Yoast SEO For TYPO3 but has now been moved to a separate extension to make it more widely accessible.

Screenshots from the documentation to have some context:

An example of a frontend request response:

{
    "body": "<h4 style=\"font-family: sans-serif;\">Welcome to a default website made with <a href=\"https:\/\/typo3.org\">TYPO3<\/a><\/h4>",
    "favicon": "https:\/\/example.com\/favicon.ico",
    "locale": "en",
    "metadata": {
        "generator": "TYPO3 CMS",
        "twitter:title": "Twitter title",
        "twitter:description": "Twitter description",
        "twitter:image": "https:\/\/example.com\/fileadmin\/_processed_\/7\/9\/csm_image_3b4afb1e67.jpg",
        "twitter:card": "summary"
    },
    "title": "Example: Content page",
    "url": "https:\/\/example.com\/content-page"
}