minor symfony#54574 [Validator] Document Compound::getConstraints options (VincentLanglet)

This PR was squashed before being merged into the 7.1 branch.

Discussion
----------

[Validator] Document `Compound::getConstraints` options

| Q             | A
| ------------- | ---
| Branch?       | 7.1
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Issues        | Fix #...
| License       | MIT

The array options is not documented in `Compoung::getConstraints`.

Looking at the usage
```
$this->getConstraints($this->normalizeOptions($options));
```
I think it should be `array<string, mixed>`.

Commits
-------

d4a99ee [Validator] Document `Compound::getConstraints` options

Author: fabpot

src/Symfony/Component/Validator/Constraint.php

@@ -121,6 +121,9 @@ public function __construct(mixed $options = null, ?array $groups = null, mixed
         }
     }
 
+    /**
+     * @return array<string, mixed>
+     */
     protected function normalizeOptions(mixed $options): array
     {
         $normalizedOptions = [];

src/Symfony/Component/Validator/Constraints/Compound.php

@@ -46,6 +46,8 @@ final public function validatedBy(): string
     }
 
     /**
+     * @param array<string, mixed> $options
+     *
      * @return Constraint[]
      */
     abstract protected function getConstraints(array $options): array;