feat: add JSON serialization configuration and change SerializerSettings visibility to public

[egyware]

• Added the ConfigureJsonSettings extension to customize JSON serialization settings in WorkflowOptions.
• Changed SerializerSettings visibility from private to public to allow external access to Newtonsoft.Json configuration.

Reason: When serializing objects like Outcome or Steps, some could not be serialized correctly. This change enables adjusting Newtonsoft.Json settings to meet specific requirements.

Describe the change A clear and concise description of what the change is. Any PR submitted without a description of the change will not be reviewed.

Describe your implementation or design How did you go about implementing the change?

Tests Did you cover your changes with tests?

Breaking change Do you changes break compatibility with previous versions?

Additional context Any additional information you'd like to provide?