Fix package references from M.E.AI packages

[stephentoub]

Microsoft Reviewers: Open in CodeFlow

[Copilot]

Pull request overview

This PR fixes package references in Microsoft.Extensions.AI packages by conditionally including certain framework-provided packages only for target frameworks older than .NET 10.0. The changes ensure that packages like System.Text.Json, System.Diagnostics.DiagnosticSource, and System.Threading.Channels are only referenced when targeting frameworks that don't include them in the base framework.

Key changes:

• Adds conditional package references for .NET 10.0 compatibility across AI libraries
• Removes System.Memory.Data package references from OpenAI and AzureAIInference projects

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
Microsoft.Extensions.AI.csproj	Adds condition to exclude System.Diagnostics.DiagnosticSource, System.Text.Json, and System.Threading.Channels for net10.0+
Microsoft.Extensions.AI.OpenAI.csproj	Removes System.Memory.Data reference and conditionally excludes System.Text.Json for net10.0+
Microsoft.Extensions.AI.AzureAIInference.csproj	Removes System.Memory.Data reference and conditionally excludes System.Text.Json for net10.0+
Microsoft.Extensions.AI.Abstractions.csproj	Adds condition to exclude System.Text.Json for net10.0+

[stephentoub]

I think the failure here will be addressed by #7078