Reinstate XML Serializer Generator tool tutorial

[gewarren]

Fixes #52693. Tool is not deprecated.

Updated tutorial to remove step to add DotNetCliToolReference item to project and tested it out.

Did run into an issue (related to dotnet/runtime#122719?) with package version 10.0.1, so kept package version at 10.0.0:

C:\Users\user.nuget\packages\microsoft.xmlserializer.generator\10.0.1\build\Microsoft.XmlSerializer.Generator.targets(51,5): warning MSB3073: The command "dotnet Microsoft.XmlSerializer.Generator "obj\Debug\net10.0\PreserializedApp.dll" --force --quiet obj\Debug\net10.0\sgen.rsp" exited with code 1.
C:\Users\user.nuget\packages\microsoft.xmlserializer.generator\10.0.1\build\Microsoft.XmlSerializer.Generator.targets(52,5): warning SGEN: Failed to generate the serializer for PreserializedApp.dll. Please follow the instructions at https://go.microsoft.com/fwlink/?linkid=858594 and try again.

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Internal previews

📄 File	🔗 Preview link
docs/core/additional-tools/xml-serializer-generator.md	Use Microsoft XML Serializer Generator on .NET
docs/navigate/tools-diagnostics/toc.yml	docs/navigate/tools-diagnostics/toc
docs/standard/serialization/xml-serializer-generator-tool-sgen-exe.md	XML Serializer Generator tool (Sgen.exe)

[Copilot]

Pull request overview

Reinstates and re-links a modern .NET tutorial for the XML Serializer Generator, and updates navigation to surface the content from the existing sgen.exe article.

Changes:

• Updated the .NET Framework sgen.exe article to point to the modern .NET XML serializer generator tutorial.
• Added a new modern .NET tutorial page for Microsoft.XmlSerializer.Generator.
• Updated TOC navigation and removed an obsolete redirect entry for the new page.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 7 comments.

File	Description
docs/standard/serialization/xml-serializer-generator-tool-sgen-exe.md	Updates the note and “See also” to link to the modern .NET generator tutorial instead of a previous-versions page.
docs/navigate/tools-diagnostics/toc.yml	Adds the new XML serializer generator tutorial to the “Additional tools” nav section.
docs/core/additional-tools/xml-serializer-generator.md	Introduces a new tutorial for using Microsoft.XmlSerializer.Generator on modern .NET.
.openpublishing.redirection.core.json	Removes a redirect that would conflict with (or hide) the new page path.