bug #38283 [Translator] Optional Intl dependency (ro0NL)

bug #38283 [Translator] Optional Intl dependency (ro0NL)

This PR was squashed before being merged into the 4.4 branch.

Discussion
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[Translator] Optional Intl dependency

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | Fix #38279
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->
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i decided to cast $locale at construct, given its property is documented to be string

Commits
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a2eb263457 [Translator] Optional Intl dependency