ROPC remediation - 11 files

[tdykstra]

Fixes #33973

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Internal previews

📄 File	🔗 Preview link
aspnetcore/migration/identity.md	Migrate Authentication and Identity to ASP.NET Core
aspnetcore/migration/proper-to-2x/membership-to-core-identity.md	Migrate from ASP.NET Membership authentication to ASP.NET Core 2.0 Identity
aspnetcore/security/app-secrets.md	[Windows](https://review.learn.microsoft.com/en-us/aspnet/core/security/app-secrets?branch=pr-en-us-33972)
aspnetcore/security/authentication/customize-identity-model.md	Identity model customization in ASP.NET Core
aspnetcore/security/authentication/identity-custom-storage-providers.md	Custom storage providers for ASP.NET Core Identity
aspnetcore/security/authentication/mfa.md	aspnetcore/security/authentication/mfa
aspnetcore/security/data-protection/implementation/key-storage-providers.md	Key storage providers in ASP.NET Core
aspnetcore/security/key-vault-configuration.md	Azure Key Vault configuration provider in ASP.NET Core

[tdykstra]

This article already discusses managed identities, only metadata was changed.

[tdykstra]

This article had already been updated, but the metadata was not updated, so there is only a metadata update here.