Support PHP attribute plugin discovery

Does that mean we have to require an explicit PHP version too? While it's always a good idea to run the latest version of software of course, I do know that many hosting companies still provide ealier versions of PHP and users don't always upgrade immediately either.

Looks good.

Ok, so 10.2.x needs PHP 8.1 to run anyway, so this looks good. I might way until 10.3 comes out before committing this one to give people at least a bit of time to upgrade.

merged, thanks!