Added a deprecation warning for the command dumper

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | yes
| Tests pass?   | yes
| Fixed tickets | #12620
| License       | MIT

This fixes #12620
Can you please:
- prefix the command description by `[DEPRECATED]`
- add E_USER_DEPRECATED as second argument here
- add `since 2.5` the the message