chore: regenerate sdk

[ChiragAgg5k]

What does this PR do?

• Refactor from Newtonsoft.Json to System.Text.Json for serialization/deserialization
• Update package dependencies in Package.csproj.twig
• Migrate all serialization/deserialization logic in Client.cs.twig, Query.cs.twig, and Extensions.cs.twig
• Update model attributes from [JsonProperty] to [JsonPropertyName] in Model.cs.twig
• Create new ObjectToInferredTypesConverter.cs.twig for proper object type handling
• Replace JsonConverter with JsonConverter<object> in ValueClassConverter.cs.twig
• Update error handling to use JsonDocument instead of JObject

Test Plan

Related PRs and Issues

• feat: migrate .NET templates to System.Text.Json + add .NET 9.0 tests sdk-generator#1085

Have you read the Contributing Guidelines on issues?

yes.