Refactor test code in Jellyfin.Extensions.Tests for clarity and consistency:
- Use explicit object initializers and collection expressions
- Standardize field naming and use of this.
- Add/improve XML doc comments for test methods
- Use new(...) syntax for Guid/Version instantiation
- Convert file-scoped to block-scoped namespaces in key tests
- Nest test classes and use instance methods in enum tests
- Enable XML docs and suppress select warnings in csproj
- No changes to test or converter logic; style and maintainability only
wjones