Update Blazor tutorials and sample apps

[guardrex]

Include 6.0 updates for Build your first Blazor tutorial on the PR.

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Document Details

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• ID: 097456af-6293-8c24-3991-fc815b94dcbf
• Version Independent ID: 978264ac-18f8-e937-30db-7050e53ac7d1
• Content: Use ASP.NET Core SignalR with Blazor
• Content Source: aspnetcore/tutorials/signalr-blazor.md
• Product: aspnet-core
• Technology: aspnetcore-tutorials
• GitHub Login: @guardrex
• Microsoft Alias: riande

[guardrex]

This was resolved by #23397.