Support ability to return compact JSON format when calling SerializeAsJsonAsync

Is your feature request related to a problem? Please describe.
I would like to obtain a compact json format when calling OpenApiSerializableExtensions.SerializeAsJsonAsync

Describe the solution you'd like
That could be done by adding an optional OpenApiJsonWriterSettings parameter to the SerializeAsJsonAsync method (with Terse = true if compact format needed)

Describe alternatives you've considered
Currently i can parse and re-serialize json to obtain a minified format but it would be better to just be able to have the right format immediately.

Additional context
I'm able to propose a pull request if needed.

从 OpenApiSerializableExtensions.SerializeAsJsonAsync 开始，检查当前如何处理 JSON writer 设置。添加对 issue 中所述可选 OpenApiJsonWriterSettings 的支持，验证 Terse 会生成紧凑 JSON，并在可用时运行现有的序列化测试。