[php-src] Issue #8022: Add brotli extension

Issue: https://github.com/php/php-src/issues/8022 Author: KapitanOczywisty ### Description Brotli encoding is firmly established successor to gzip, and from 2017 supported by [every major browser](https://caniuse.com/?search=brotli), as well server side (apache, ngnix, nodejs). Even curl used in php can be compiled with Brotli. Adding Brotli extension to php should follow that. There is 3rd party extension https://github.com/kjdev/php-ext-brotli , but it's not even listed in PECL. However I think it should be bundled with php anyway, as optional extension - at least for now. This would allow wide adoption of this encoding and integration within php (e.g. ob_brhandler, Phar::BR). I don't have sufficient knowledge to make PR and I'm not willing to deal with RFC process, but I hope there is someone who will get excited about that idea and can make this happen. I'll offer any help I can give.