Support for extensions containing Roslyn features (analyzers, refactorings)

## Context

I have an extension that contains custom Roslyn analyzers, refactorings and code fixes. I use OmniSharp settings to configure it:

```json
{
"RoslynExtensionsOptions": {
"EnableAnalyzersSupport": true,
"LocationPaths": [
]
}
}
```

OmniSharp is now not used by default, so now I have to:

- Set `dotnet.server.useOmnisharp` to `true`
- Disable C# Dev Kit

## Question

Is it possible to configure custom Roslyn analyzers and refactorings without using OmniSharp?

## Versions used
VS Code: `1.85.1`
C# extension: `2.14.8`
C# Dev Kit: `1.2.5`