fix(doctrine): honor castToArray and schema in filter OpenAPI parameters

[soyuka]

Q	A
Branch?	4.3
Bug fix?	yes
New feature?	no
Deprecations?	no
Issues	Fixes #8406
License	MIT
Doc PR	n/a

What

OpenApiFilterTrait::getOpenApiParameters() (used by ExactFilter, PartialSearchFilter, IriFilter, SortFilter, OrFilter) had two problems:

1. It returned a singular parameter whenever a scalar schema was set, ignoring castToArray — so castToArray: true produced a singular parameter, and the default (null → both singular + array) was never reached for scalar-typed parameters.
2. The singular OpenApiParameter was built without its declared schema, so an explicit schema: ['type' => 'integer'] was dropped.

castToArray is now the sole control, and the schema is always passed through:

• castToArray === false → singular only
• castToArray === true → array only
• castToArray === null (default) → both
• the singular parameter carries the declared schema; the array parameter's schema is the declared one when already type: array, else ['type' => 'array', 'items' => <schema>].

Behavior change

A scalar-typed parameter with default castToArray now exposes both key and key[] (previously singular-only when a scalar schema was set). This matches the old SearchFilter behavior and the documented default. Consequence: a boolean ExactFilter with schema: ['type' => 'boolean'] and no castToArray now also emits key[]; set castToArray: false for a single parameter (the docs are being updated accordingly).

Test

ExactFilterSchemaParameterTest asserts the OpenAPI output for the four cases from the issue (scalar + default → both; castToArray: true → array only; castToArray: false → singular only; explicit array schema + castToArray: true → single array, no duplicate). Fails on 2/4 before the fix, all green after. Full tests/Functional/Parameters/ + OpenApiTest suites green; php-cs-fixer clean; PHPStan [OK].