Update dependencies for ReactiveUI 21.0.1

[ChrisPulman]

What kind of change does this PR introduce?

update

What is the new behavior?

This pull request introduces significant improvements to the ReactiveUI Uno codebase, focusing on enhanced test coverage, better platform integration, and modernization of dependencies. The most important changes include the addition of a dedicated test project with comprehensive tests, new builder extension methods for Uno and Uno.WinUI platforms, and various dependency and documentation updates.

Test infrastructure and coverage:

• Added a new ReactiveUI.Uno.Tests project targeting net9.0, including test dependencies and references, and integrated it into the solution file. [1] [2] [3]
• Implemented new unit tests for converters (BooleanToVisibilityTypeConverterTests.cs), binding hooks (AutoDataTemplateBindingHookTests.cs), and platform operations (PlatformOperationsTests.cs) to improve coverage and reliability. [1] [2] [3]

Platform integration and builder extensions:

• Introduced UnoReactiveUIBuilderExtensions and UnoWinUIReactiveUIBuilderExtensions to provide platform-specific configuration and scheduler integration for Uno and Uno.WinUI, respectively. [1] [2]
• Updated dependency registration in ActivationHelper.cs to use AppLocator for improved platform compatibility.

Dependency and compatibility updates:

• Updated test and main package dependencies (e.g., ReactiveUI, xunit, FluentAssertions, coverlet.msbuild) to more recent versions and enabled test package references for test projects. [1] [2]
• Adjusted target frameworks in Directory.build.props to remove unused platforms and focus on supported ones.

Documentation and code quality:

• Improved and clarified XML documentation for enums and converters, and refactored property registration in RoutedViewHost for clarity and correctness. [1] [2] [3]
• Minor improvements to logging and error messages for better developer experience.

These changes collectively enhance the maintainability, testability, and platform support of the ReactiveUI Uno codebase.

What might this PR break?

This is a part of a breaking change

Please check if the PR fulfills these requirements

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

Other information:

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[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.