XS✔ ◾ Added .NET 10 dual targeting

[MaxDac]

This pull request updates the supported .NET versions to include .NET 10, resolving the conflicts in compilation and unit testing, keeping the older framework support unchanged.

In the following, the implementation details:

• Missing packages were added in the reference group which targets the older framework.
• Added precise namespace to identify the method currently used in the HostBuilderExtensions class.
• Made reference to System.Linq.Async package conditional to every framework except .NET 10: this condition does not make use of the alias defined in the Directory.Build.props as it is a specific issue related to .NET 10 where the method used from the package has been included in the Framework itself.

[github-actions]

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	Lines
Product Code	4
Test Code	14
Subtotal	18
Ignored Code	41
Total	59

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[Copilot]

Pull request overview

This PR adds .NET 10 as a target framework alongside the existing .NET 9 support, enabling multi-targeting compilation and testing. The changes address framework-specific compatibility issues including namespace conflicts and built-in functionality that replaces external packages in .NET 10.

• Updates the latest supported .NET version from 9.0 to 10.0 in build configuration
• Adds package references for older framework support (Microsoft.FeatureManagement and System.Linq.Async)
• Works around namespace conflicts by using fully qualified names where .NET 10 introduces conflicting types
• Conditionally excludes System.Linq.Async package for .NET 10 since the functionality is now built into the framework

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
Directory.Build.props	Updates LatestSupportedDotNetVersion property from net9.0 to net10.0 to enable .NET 10 targeting
Directory.Packages.props	Adds Microsoft.FeatureManagement and System.Linq.Async package versions to the "Previous DotNet Package Versions" section for .NET 9 compatibility
src/Hosting.Services.Web/HostBuilderExtensions.cs	Fully qualifies Validation.ThrowIfNullOrWhiteSpace calls to resolve namespace conflict introduced in .NET 10
tests/FeatureManagement.UnitTests/Microsoft.Omex.Extensions.FeatureManagement.UnitTests.csproj	Adds conditional exclusion of System.Linq.Async package for net10.0 since the functionality is built into the framework

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[K-Cully]

The package references need to be fixed.
The current change reverts all 9.x builds to use 8.x dependencies.

[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 4 comments.