[Security\Csrf] Split CsrfTokenGenerator into CsrfTokenManager and TokenGenerator

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #9210
| License       | MIT
| Doc PR        | -

This is a follow-up PR of #6554 that splits the CsrfTokenGenerator into two separate classes for generating and managing CSRF tokens. As a consequence, it is now possible to explicitly remove or refresh CSRF tokens if they should be used only once. See #9210 for more information.