[make:registration] use "User" type in EmailVerifier::class

[jrushlow]

sendEmailConfirmation() && handleEmailConfirmation() both have the $user type as UserInterface. This is pointless other than to ensure we get a "user" object. Seeing as we already know the class details of the "user" object, let's use the class short name instead of UserInterface when generating EmailVerifier. Improves phpstan in userland.

// in part

- public function sendEmailConfirmation(UserInterface $user)
+ public function sendEmailConfirmation(<?= $user_class_name ?> $userl)  // generated as "User"

• adds (string) cast to getId() calls on the user object. In cases where the users id is an int, this will squash any squawks from phpstan about

Parameter #2 $userId of method SymfonyCasts\Bundle\VerifyEmail\VerifyEmailHelperInterface::generateSignature() expects string, int|null given. 

Edge Case

If the consumer has multiple "user" objects that use these methods (out of scope for MakerBundle), they can change the type manually to either User|AnotherUser $user || CustomUserInterface $user.