Upgrade to .NET 10.0 and update dependencies

Updated target frameworks to include .NET 10.0 and removed support for .NET 6.0. Upgraded package references to their latest versions, including `Microsoft.Extensions.*`, `Microsoft.NET.Test.Sdk`, and `xunit.runner.visualstudio`. Bumped `FeatureMasterX` version to 10.0.0 and updated release notes accordingly.

Refactored `ListCheckFeatureFilterProvider.cs` to use nullable dictionary values in `ConfigurationBuilder.AddInMemoryCollection`. Made minor formatting adjustments in project files.

Refactor BaseUnitTest to improve dependency injection setup

- Refactored AddScoped dependency Injection.
- Ensured proper configuration loading from `appsettings.json`.
- Improved code readability and maintainability by organizing internal fields and private methods.