[Feature Request]: BuildCheck diagnostics look different than 'normal' build diagnostics

### Summary

BuildCheck diagnostics don't have the kind of structured formatting that project-specific diagnostics have, so they look out of place and jarring:

```terminal
> dotnet build /analyze
MSBUILD : warning : C:\Users\chethusk\Code\Scratch\msbuild-analyzer-examples\double-writes\double-writes.csproj (12,5): BC0102: Tasks Copy and Copy from projects double-writes.csproj and double-writes.csproj write the same file: C:\Users\chethusk\Code\Scratch\msbuild-analyzer-examples\double-writes\obj\storage\Class1.cs.
double-writes succeeded with 1 warning(s) (0.4s) → bin\Debug\net8.0\double-writes.dll
C:\Users\chethusk\Code\Scratch\msbuild-analyzer-examples\double-writes\double-writes.csproj(16,5): warning XTRA0123: Nuh uh!

Build succeeded with 2 warning(s) in 0.9s
```

This error duplicates the project file path, and it has an unnecessary `MSBUILD` prefix compared to the XTRA0123 warning I created.

### Background and Motivation

We should attempt as much as possible to have uniform rendering of diagnostics - even if the 'groupings' of the diagnostics are different (whole-build vs per-project).

### Proposed Feature

Analyzer diagnostics should as much as possible have the same formatting as existing per-project diagnostics.

### Alternative Designs

_No response_