Add a section about signalr service an auth

[javiercn]

SignalR Service captures the list of claims during _negotiate and serializes them. That might result in the ClaimsPrincipal being different locally vs when using the SignalR service. We should have a mention about that in here and provide further guidance about how to normalize the set of claims between prerendering, initial authentication and signalr service re-connection.

---

Document Details

⚠ Do not edit this section. It is required for docs.microsoft.com ➟ GitHub issue linking.

• ID: 3eddf2de-7e50-5680-ff2d-a4307f26b5c0
• Version Independent ID: 673f220c-ad49-bd27-5d74-3a9c44747cba
• Content: Host and deploy ASP.NET Core Blazor Server
• Content Source: aspnetcore/host-and-deploy/blazor/server.md
• Product: aspnet-core
• Technology: aspnetcore-hostdeploy
• GitHub Login: @guardrex
• Microsoft Alias: riande