Fixed passing DateTime instances into DoctrineDatabase::findBy() methods

[Steveb-p]

🎫 Issue	IBX-XXXXX

Description:

This PR aims to fix an issue where specific types representing database values - namely, DateTimeInterface in context of Doctrine DBAL date & time types - are not working properly.

This allows for example:

$gateway->findBy(['date' => new DateTimeImmutable('2025-01-01 00:00:00']),

as well as using Comparison operators with date time objects, without formatting them explicitly in the gateway/handler.

use Doctrine\Common\Collections\Expr\Comparison

$gateway->findBy([new Comparison('field', '>', new DateTimeImmutable('2025-01-01 00:00:00'))]),

Reported deprecations are due to Doctrine internal calls, which we are mocking during tests.

For QA:

Documentation: