Disallow empty file in FileValidator
feature #11125 [Validator] Disallow empty file in FileValidator (megazoll)

This PR was merged into the 2.3-dev branch.

Discussion
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[Validator] Disallow empty file in FileValidator

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | yes
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        | symfony/symfony-docs#3746

Commits
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1b253cb Disallow empty file in FileValidator