Fix property access for field mapping type

[Chris53897]

Will address
19x: Using ArrayAccess on Doctrine\ORM\Mapping\FieldMapping is deprecated and will not be possible in Doctrine ORM 4.0. Use the corresponding property instead. (ArrayAccessImplementation.php:31 called by FieldFactory.php:180, https://github.com/doctrine/orm/pull/11211, package doctrine/orm)

[Chris53897]

I have converted it to draft.
The --prefer-lowest run will fail, if i just update to new syntay.
I tried to bump some min-versions but without success.
And a check with composer is to slow.

[javiereguiluz]

This is the fix we use in other parts of the code:

EasyAdminBundle/src/Orm/EntityRepository.php

Lines 301 to 310 in e373893

	// In Doctrine ORM 3.x, FieldMapping implements \ArrayAccess; in 4.x it's an object with properties
	$fieldMapping = $associatedEntityDto->getClassMetadata()->getFieldMapping($propertyName);
	// In Doctrine ORM 2.x, getFieldMapping() returns an array
	/** @phpstan-ignore-next-line function.impossibleType */
	if (\is_array($fieldMapping)) {
	/** @phpstan-ignore-next-line cast.useless */
	$fieldMapping = (object) $fieldMapping;
	}
	/** @phpstan-ignore-next-line function.alreadyNarrowedType */
	$propertyDataType = property_exists($fieldMapping, 'type') ? $fieldMapping->type : $fieldMapping['type'];

It's a bit convoluted 😐 but it covers Doctrine ORM 2.x, 3.x and 4.x.