[WCM] Skip console commands from event listeners

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes (symfony/symfony#9235)
| Applies to    | master
| Fixed tickets | none
[Translation] added method to expose collected message
[OptionsResolver] Adjusted the OptionsResolver documentation to describe the 2.6 API
Added missing mailer class and use statements
Removed duplicate use statements
intro the var-dumper component
review effect
Reduce line length
Replace addViolationAt (deprecated) by buildViolation
Update Callback.rst

"Symfony\Component\Validator\ExecutionContextInterface" namespace is deprecated, new namespace should be "Symfony\Component\Validator\Context\ExecutionContextInterface"
Don't use deprecated functions in Callback.rst

The addViolationAt function is marked as deprecated and should be replaced by buildViolation according to the Symfony update guides.
Update custom_contraint.rst to meet the new 2.5 api
added a versionadded comment to Callback.rst
Adding details about the 2.4 API as comments
Adding a section about keeping BC in a re-usable bundle
Fixes thanks to @xabbuh
Minor tweaks and a missing location thanks to xabbuh and WouterJ
[#4233][#4094] Making validateValue and validate changes
doc for Dumpers
split intro/advanced sections