[Feature Request]: Allow silencing Messages entirely

### Summary

We have flags to upgrade Warnings to Errors, and downgrade Warnings to Messages, but we do not have a way to completely silence a Message. This is a hole in our overall diagnostic-management utilities, and can be relevant for tools that are looking for certain format of message.

### Background and Motivation

See https://github.com/dotnet/sdk/pull/36329 for an example of when this would be useful. The Substrate build inspects message content and triggers errors for output that looks like an MSBuild Diagnostic, and they have no way to silence that built-in to MSBuild currently.

### Proposed Feature

```xml
list;of;message;ids
```

Something similar to this.

### Alternative Designs

_No response_