Generate setters for Datetime and fixed point decimal that check if the value has *really* changed

[allan-simon]

Summary

maker bundle should generate sensible setters to avoid people falling in a common pitfall

Context

As of January 2022, doctrine has a 'logical but confusing' behaviour

doctrine/orm#5542
doctrine/orm#1924

it's because of this line https://github.com/doctrine/orm/blob/bd949312016be418c36603d89951b9641f79ffdb/lib/Doctrine/ORM/UnitOfWork.php#L660

that does a === comparison, so for an object, it compares the reference and not the value
so admitting you have an entity Employee with arrival date 2021-01-01 and firstname robert

doing

$employee->setFirstname('robert');
$em->persist($employee);
$em->flush()

-> it does not generate a SQL request because the value was robert and it hasn't changed

but going

$employee->setArrivalDate(new \Datetime('2021-01-01'));
$em->persist($employee);
$em->flush()

-> it generates a new request because this is a new object though the date hasn't changed

a workaround waiting an official solution from doctrine/orm#5542

is to do a check manually in the setter (so we do it once and for all) and not change if "equal" in a logical (same datetime/same amount)

currently at least decimal and datetime fields are concerned (datetime because a new reference is created, decimal because a strict string comparison is not sufficient , i.e '0' and '0.0' will generate a UPDATE though they're actually a real value )

Proposed solutions

1. simply add a warning comment in the setter

    public function setLinkedAt(\DateTimeInterface $linkedAt): self
    {
             // warning, this may generate unecessary update: see *link*
            $this->linkedAt = $linkedAt;

            return $this;
    }

2. we could more opinionated (like we are for some other types that generates more complex setters already) 

we could generate

    public function setLinkedAt(\DateTimeInterface $linkedAt): self
    {
        // we do this because :  *link explaining the issue* 
        if ($this->linkedAt != $linkedAt) {
            $this->linkedAt = $linkedAt;
        }
     
        return $this;
    }