Add alias for serializeFormInterface

[Bukashk0zzz]

Fix issue with Symfony 6.1 and error: call_user_func_array(): Argument #1 ($callback) must be a valid callback, class JMS\Serializer\Handler\FormErrorHandler does not have a method "serializeFormInterfaceTojson"

[mbabker]

I'd actually say the fix belongs in the Serializer package, not here. When schmittjoh/serializer#1362 added support for the interface, it didn't define explicit methods, which would cause it to fall back to JMS\Serializer\Handler\HandlerRegistry::registerSubscribingHandler() creating the default method names that don't exist.

[goetas]

solved in https://github.com/schmittjoh/serializer/pull/1432