fix: Failing to retrieve reflection property on enum

[Goazil]

This PR should fix an issue with the property isPrivate from inheritance on ReflectionProperty.

In EnumReflectionProperty the method isPrivate should be executed on the originalReflectionProperty to prevent fatal error :

Internal error: Failed to retrieve the reflection object

This commit just override the method and check the privacy on the originalReflectionProperty.

[greg0ire]

Please cover this with a test in https://github.com/doctrine/persistence/blob/3.3.x/tests_php81/Persistence/Reflection/EnumReflectionPropertyTest.php

[Goazil]

Please cover this with a test in https://github.com/doctrine/persistence/blob/3.3.x/tests_php81/Persistence/Reflection/EnumReflectionPropertyTest.php

Thanks, done.

[greg0ire]

Please kindly squash your commits together. If you don't, we'll try to remember to do it for you but it's best if you save us this trouble.

How to do that?

1. git rebase -i origin/3.3.x, assuming origin is a git remote that points to this repository, and not your fork. If you're not sure what your remotes are, run git remote -vvv, there should be your fork and the holy/reference/base/origin/whatever-you-call-it repository.
2. A window will show up with many lines, replace pick with fixup on every line but the first one
3. Close your editor, git should do its magic, and you should end up with one commit
4. Use git push --force to overwrite what you already push. Don't forget the --force option otherwise git will try to merge both things together.

[greg0ire]

Thanks @Goazil