Add Metrics for Blazor

[danroth27]

We should continue the work we started in .NET 8 of adding Metrics to ASP.NET Core by defining and implementing Metrics for Blazor.

• [Pre5] New Blazor metrics AspNetCore.Docs#35278
• Blazor - rendering metrics and tracing #61609

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We're moving this issue to the .NET 9 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
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