And disallow all requests that are not static content.

According to the docs in
https://httpd.apache.org/docs/current/rewrite/flags.html#flag_l using
[L] in an .htaccess context incurs the risk of infinite recursion,
which is exactly what we were seeing in production for non-existing
.php files. Use [END] instead.

Update the WP Multisite section according to
https://wordpress.org/support/article/htaccess/#wordpress-3-5-and-up

Add the 'intl', 'imagick' and 'zip' modules, which are not required
but recommended, and may actually be useful.

Fixes issue ai/noblogs-wp#89.

These should help with converting widgets from legacy to
new 'blocks'.

Merges the contents of ai3/docker/noblogs (composer branch).