.Net: Bug: Custom JsonSerializerOptions passed to kernel plugins are not used.

[ascott18]

Describe the bug
Custom JsonSerializerOptions passed to kernel plugins are not used.

To Reproduce
Steps to reproduce the behavior:

1. Create and use a kernel plugin that was created with custom JSON options:

KernelPluginFactory.CreateFromType<PersonKernelPlugin>(
    new JsonSerializerOptions { /* desired custom JSON settings */ },
    "Person"
)

2. Expect those settings to be used to serialize kernel function results
3. Observe in the SK source code that this is not the case - instead, a static, immutable, inaccessible set of JSON options are used instead: https://github.com/microsoft/semantic-kernel/blob/main/dotnet/src/InternalUtilities/connectors/AI/FunctionCalling/FunctionCallsProcessor.cs#L503-L515

Expected behavior
Custom JSON options are used so that my results are serialized as expected according to my customizations (custom converters, null handling, loop handling, etc).

Platform

• Language: C#
• Source: NuGet Microsoft.SemanticKernel 1.57.0
• AI model: N/A
• IDE: N/A
• OS: N/A

Additional context
Add any other context about the problem here.