Deprecate interface Symfony\Component\Validator\ExecutionContextInterface

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | yes
| Tests pass?   | yes
| Fixed tickets | [#12683]
| License       | MIT

Deprecate interface Symfony\Component\Validator\ExecutionContextInterface
Please keep 2.5 here (and put it in the above message also)