Deprecated max_length and pattern options
feature #10001 [Form] Deprecated max_length and pattern options (stefanosala)

This PR was squashed before being merged into the 2.5-dev branch (closes #10001).

Discussion
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[Form] Deprecated max_length and pattern options

Split of issue #9759

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | `max_length` and `pattern` in form options
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | https://github.com/symfony/symfony-docs/pull/3461

Commits
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52c07c7 Deprecated max_length and pattern options