[Hackday][Validator] Add deprecated logs on addViolation() and addViolationAt() methods.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | yes
| Tests pass?   | yes
| Fixed tickets | #12686 
| License       | MIT
| Doc PR        | 
I'm not sure if this log is useful because the whole class and the interface are deprecated, as they were moved to the `Symfony\Component\Validator\Context` namespace.