Update Nimble / Spright Blazor to .NET 8

[msmithNI]

Pull Request

🤨 Rationale

Resolves #1667

• Split off resolving more code analysis suppressions to Fix / re-evaluate Blazor disabled code analysis rules #2453
• Blazor EventCallbacks are not invoked with apps using .NET 8 template #2355 : Resolved by updates to Nimble/Spright JS initialization scripts for .NET 8
• Possible race condition showing Blazor NimbleDialog during OnAfterRenderAsync #2188 : Not reproducible by Nimble team, can debug further once changes published if client can still reproduce

👩‍💻 Implementation

• Projects in Blazor solution now target net8.0 (formerly net6.0)
• Update other .NET dependencies, and code analyzer package versions
• Update docs
• Re-build Demo.Server example based on new Blazor Web App template
• Update acceptance test projects to use similar setup as Blazor Web App templates
• NimbleBlazor.Tests.Acceptance.Client: Existing tests use the InteractiveServer render mode. The project also now supports tests using InteractiveWebAssembly and static SSR render modes. Add one example test for each.
  • TODO: Spright acceptance test project currently don't use the new setup yet. If the changes look reasonable and we want to do the same for the Spright tests, I can do so in an update.

🧪 Testing

• Manual testing
• Autotests (unit/acceptance) pass. New tests for Nimble for InteractiveWebAssembly / static SSR render modes.

✅ Checklist

• I have updated the project documentation to reflect my changes or determined no changes are needed.

[msmithNI]

@atmgrifter00 can you buddy this PR?

[jattasNI]

Feedback from initial testing, haven't looked at the code yet

[jattasNI]

Working my way through the changes, about 1/3 done

[rajsite]

pushing current comments relevant to open discussions

[jattasNI]

Finished per-file review, just want to take another look when the main open threads are resolved.

[msmithNI]

@jattasNI @rajsite open discussion threads should be resolved, so feel free to re-review.