[Platform] Support streaming output for Ollama

[logicalor]

Currently, if you set stream to true when setting Ollama options it will throw an error.

example:

$result = $agent->call(
    $messages, [
        'stream' => true,
    ]
);

results in:

PHP Fatal error:  Uncaught Symfony\Component\HttpClient\Exception\JsonException: Syntax error for "http://localhost:11434/api/chat". in /.../vendor/symfony/http-client/Response/CommonResponseTrait.php:90
Stack trace:
#0 /.../vendor/symfony/ai-platform/src/Result/RawHttpResult.php(28): Symfony\Component\HttpClient\Response\AsyncResponse->toArray()
#1 /.../vendor/symfony/ai-platform/src/Bridge/Ollama/OllamaResultConverter.php(47): Symfony\AI\Platform\Result\RawHttpResult->getData()
#2 /.../vendor/symfony/ai-platform/src/Result/ResultPromise.php(48): Symfony\AI\Platform\Bridge\Ollama\OllamaResultConverter->convert()
#3 /.../vendor/symfony/ai-platform/src/Result/ResultPromise.php(37): Symfony\AI\Platform\Result\ResultPromise->await()
#4 /.../vendor/symfony/ai-agent/src/Agent.php(82): Symfony\AI\Platform\Result\ResultPromise->getResult()
#5 /.../src/app.php(26): Symfony\AI\Agent\Agent->call()
#6 {main}
  thrown in /.../vendor/symfony/http-client/Response/CommonResponseTrait.php on line 90