feat: upgrade to PHP 8.2RC6 and use the official PHP builds

[dunglas]

Upgrade to PHP 8.2RC6 and don't compile our own PHP now that docker-library/php#1342 and docker-library/php#1331 are merged.

[withinboredom]

This won't work, at least for alpine images because it doesn't build libphp.so and they don't seem to want to add it because it adds too much to the image size.

[jamogriff]

This breaks seamless PECL support on Alpine, fyi:
RUN pecl install xdebug
pecl/xdebug requires PHP (version >= 7.2.0, version <= 8.1.99), installed version is 8.2.0RC6

[withinboredom]

@jamogriff it's broken everywhere, even using install-php-extensions xdebug won't work. Xdebug isn't compatible with PHP 8.2, so it can't be installed.