Policy-based authorization article overhaul

[guardrex]

Fixes #35817

Tom ... I worked quite long time on this one, longer than usual. The current article (live link) seems like it has a lot of problems to address.

Notes

• I'll ping Wade when he gets back to look everything over for a possible patch PR later. Unless you think we need it, I don't plan on requesting an engineering review.
• Per Dan's request, I'm moving the RP and MVC content to their own articles under their nodes. The main doc set article uses Blazor examples.
• The Blazor code cross-links pull from the new Blazor authz sample app in the main samples repo, which I'm using to cover all of the scenarios in the security > authorization node (Dan's original master issue). I didn't do much with the old samples. I stripped namespaces in some of the code. Those old samples still provide sample code in the main doc set article, which is focused on Blazor, and the non-Blazor namespaces in those old samples confuse the presentation.
• I took a heavy hand with section ordering, section naming, and content phrasing throughout the article. I'm 👂 for your bug fixes and suggestions.
• I 💀 the INCLUDES content approach. No broken links in prior version content now. 🎉

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📄 File	🔗 Preview link
aspnetcore/migration/22-to-30.md	aspnetcore/migration/22-to-30
aspnetcore/migration/70-to-80.md	aspnetcore/migration/70-to-80
aspnetcore/mvc/security/authorization/policies.md	aspnetcore/mvc/security/authorization/policies
aspnetcore/mvc/security/authorization/resource-based.md	aspnetcore/mvc/security/authorization/resource-based
aspnetcore/razor-pages/security/authorization/policies.md	aspnetcore/razor-pages/security/authorization/policies
aspnetcore/razor-pages/security/authorization/resource-based.md	aspnetcore/razor-pages/security/authorization/resource-based
aspnetcore/release-notes/aspnetcore-5.0.md	aspnetcore/release-notes/aspnetcore-5.0
aspnetcore/security/authorization/custom-authorization-policies-with-iauthorizationrequirementdata.md	aspnetcore/security/authorization/custom-authorization-policies-with-iauthorizationrequirementdata
aspnetcore/security/authorization/customizingauthorizationmiddlewareresponse.md	aspnetcore/security/authorization/customizingauthorizationmiddlewareresponse
aspnetcore/security/authorization/dependencyinjection.md	aspnetcore/security/authorization/dependencyinjection
aspnetcore/security/authorization/iauthorizationpolicyprovider.md	aspnetcore/security/authorization/iauthorizationpolicyprovider
aspnetcore/security/authorization/policies.md	aspnetcore/security/authorization/policies
aspnetcore/security/authorization/resource-based.md	aspnetcore/security/authorization/resource-based
aspnetcore/security/how-to-choose-identity-solution.md	aspnetcore/security/how-to-choose-identity-solution
aspnetcore/toc.yml	aspnetcore/toc

[Copilot]

Pull request overview

This PR modernizes and restructures the policy-based authorization documentation by shifting MVC and Razor Pages–specific guidance into their own new articles and refocusing the main article on Blazor-oriented examples, while also updating related cross-references and Entra ID links across the docs set.

Changes:

• Overhauls security/authorization/policies.md to use Razor component examples and updated samples (including a new external-service sample section).
• Adds new companion articles for MVC and Razor Pages policy-based authorization and wires them into aspnetcore/toc.yml.
• Updates multiple related docs to point to the new anchors/pages and refreshes Microsoft Entra ID links + ms.date metadata.

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
aspnetcore/toc.yml	Adds TOC entries for the new MVC and Razor Pages policy-based authorization articles.
aspnetcore/security/how-to-choose-identity-solution.md	Updates Entra link + ms.date metadata.
aspnetcore/security/authorization/resource-based.md	Updates xref fragments and sample namespace/path text to match the new policies doc structure.
aspnetcore/security/authorization/policies/samples/stubs/copy_of_IAuthorizationService.cs	Removes copied framework source stub previously used for an include snippet.
aspnetcore/security/authorization/policies/includes/policies5.md	Removes pre-6.0 include content that was previously injected into the policies article.
aspnetcore/security/authorization/policies.md	Major rewrite: policy concepts + Blazor-focused examples + new external-service sample walkthrough.
aspnetcore/security/authorization/iauthorizationpolicyprovider.md	Updates xref fragments + ms.date.
aspnetcore/security/authorization/dependencyinjection.md	Updates xref fragments + ms.date.
aspnetcore/security/authorization/customizingauthorizationmiddlewareresponse.md	Updates ms.date.
aspnetcore/security/authorization/custom-authorization-policies-with-iauthorizationrequirementdata.md	Replaces hard-coded user values with placeholders in decoded JWT example.
aspnetcore/release-notes/aspnetcore-5.0.md	Updates Entra link + ms.date.
aspnetcore/razor-pages/security/authorization/resource-based.md	Updates xref fragment to new policies doc anchor.
aspnetcore/razor-pages/security/authorization/policies.md	New Razor Pages–specific policy-based authorization article.
aspnetcore/mvc/security/authorization/resource-based.md	Updates xref fragment to new policies doc anchor.
aspnetcore/mvc/security/authorization/policies.md	New MVC-specific policy-based authorization article (including MVC handler Resource guidance).
aspnetcore/migration/70-to-80.md	Updates xref to point to the new MVC policies article section.
aspnetcore/migration/22-to-30.md	Updates xrefs to the new policies anchor/article for handler resource guidance.