[Config] Allow extra hint in exception message
feature #11453 [Config] Allow extra hint in exception message (WouterJ)

This PR was squashed before being merged into the 2.6-dev branch (closes #11453).

Discussion
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[Config] Allow extra hint in exception message

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #1666
| License       | MIT
| Doc PR        | symfony/symfony-docs#4047

Commits
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3062b3e [Config] Allow extra hint in exception message