[CodingStyle] Handle null item on ManualJsonStringToJsonEncodeArrayRector

[samsonasik]

Given the following code:

$json = '{"a":null}';

It got error:

1) Rector\Tests\CodingStyle\Rector\Assign\ManualJsonStringToJsonEncodeArrayRector\ManualJsonStringToJsonEncodeArrayRectorTest::test with data set #0 (Symplify\SmartFileSystem\SmartFileInfo Object (...))
Rector\Core\Exception\NotImplementedYetException: Not implemented yet. Go to "Rector\Core\PhpParser\Node\NodeFactory::createArrayItem()" and add check for "" node.

This patch fix it .

[samsonasik]

All checks have passed 🎉 @TomasVotruba it is ready for review.

[TomasVotruba]

Thank you