[make:user] add class name for UniqueConstraint

[seb-jean]

Sometimes we can have multiple user classes and the index name is then duplicated if we don't change it manually. I added this PR to fix this by prefixing with the class name.

For instance:
I have an Admin and User entity that I generated with make:user. The email field is used for this index.

Before:
I will then have #[ORM\UniqueConstraint(name: 'UNIQ_IDENTIFIER_EMAIL', fields: ['email'])] for User and Admin entities

After:
For the User entity, this will be:
#[ORM\UniqueConstraint(name: 'USER_UNIQ_IDENTIFIER_EMAIL', fields: ['email'])]

For the Admin entity, this will be:
#[ORM\UniqueConstraint(name: 'ADMIN_UNIQ_IDENTIFIER_EMAIL', fields: ['email'])]