Add "is" getter type support

[ScorpioT1000]

example:

class A {
    protected $ready = false;

    public function isReady() { return $this->ready; }
}

doctrine-orm-transformations/src/Traits/Transformable.php

Line 59 in 3fb41c2

$getter = $policy->getter ?: 'get'.ucfirst($pn);