…ustom) error message

…meter in (custom) error message (seho-nl, Sebastien Hoek)

This PR was squashed before being merged into the 5.4 branch.

Discussion
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[Validator] [UniqueValidator] Use correct variable as parameter in (custom) error message

| Q             | A
| ------------- | ---
| Branch?       | 5.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Issues        |
| License       | MIT

Unique constraint should use the `$element` (the element violating uniqueness) and not `$values` (the collection) to build the error message.

When adding a custom message to the Constraint, for example
`message: 'Duplicate element found with value {{ value }}'`
It outputs:
`Duplicate element found with value "array"`
And the expected output should be:
`Duplicate element found with value "main"` (where main is an example value in the collection).

Commits
-------

8ef75c2c01 [Validator] [UniqueValidator] Use correct variable as parameter in (custom) error message

* 5.4: (21 commits)
  [SecurityBundle] Add `provider` XML attribute to the authenticators it’s missing from
  [DoctrineBridge] Test reset with a true manager
  Sync php-cs-fixer config file with 7.2
  [HttpClient] Fix parsing SSE
  [Notifier] Fix thread key in GoogleChat bridge
  [HttpKernel][Security] Fix accessing session for stateless request
  [Serializer] Fix `ObjectNormalizer` with property path
  test handling of special "value" constraint option
  [PhpUnitBridge] Add missing import
  [FrameworkBundle] Fix setting default context for certain normalizers
  [57251] Missing translations for Romanian (ro)
  [ErrorHandler] Fix rendered exception code highlighting on PHP 8.3
  [String] Fix #54611 pluralization of -on ending words + singularization of -a ending foreign words
  [Validator] [UniqueValidator] Use correct variable as parameter in (custom) error message
  [Messenger] Comply with Amazon SQS requirements for message body
  fix cssColor HSLA test dataProvider
  properly handle invalid data for false/true types
  chore: upgrade class doc
  add space in error message
  [Messenger] [Amqp] Handle AMQPConnectionException when publishing a message.
  ...