Add PHPDoc @template to Collections

[AAllport]

It's not uncommon for Laravel developers to use tools such as PHPStan to ensure code quality

I am proposing the addition of the @template PHPDoc to collections to allow developers to enforce stricter standards throughout Laravel projects.
This would change only the PHPDocs, and as such, will not be a breaking change!

More information can be found here: https://phpstan.org/blog/generics-in-php-using-phpdocs

[AAllport]

Hm, though my post the other day had vanished, not the case, closing as a duplicate of #34110