Deeper MSBuild logging integration

[TheAngryByrd]

Is your feature request related to a problem? Please describe.

After #241 goes in, it would probably make sense to ship our own MsBuild Task implementation so we can output correct message levels to MsBuild itself.

Describe the solution you'd like

Some mapping layer from our ILogger to MsBuild's Events: https://learn.microsoft.com/en-us/visualstudio/msbuild/task-writing?view=vs-2022#raise-events-from-a-task

Describe alternatives you've considered

Not doing it.

Additional context

[baronfel]

Some prior art for smart, ILogger-aware MSBuild logging: https://github.com/dotnet/sdk/tree/main/src/Microsoft.Extensions.Logging.MSBuild