[Validator] Added hasser support for entity method validation
feature #9097 [Validator] Added hasser support for entity method validation (bicpi)

This PR was squashed before being merged into the 2.5-dev branch (closes #9097).

Discussion
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[Validator] Added hasser support for entity method validation

Hasser support was added in addition to existing getter and isser support for more consistency between components

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | symfony/symfony-docs#3418

Commits
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e8b6978 [Validator] Added hasser support for entity method validation