Add callable support to $query->fetch()

[adamkiss]

This PR …

This PR adds a support for type callable in the $database->fetch() method. This allows using existing functions/methods without having to rewrap them in a Closure.

// while having a class/function to render a database row
$query->fetch([SomeClass::class, 'renderRow'])->all();
$query->fetch('SomeClass::renderRow')->all()

Ready?

• Unit tests for fixed bug/feature
• In-code documentation (wherever needed)
• Tests and checks all pass

For review team

• Add changes to release notes draft in Notion
• Add to website docs release checklist (if needed)

[adamkiss]

I can review?? (edit: GitHub confused me for a moment) :D

thanks for merging.