[FEATURE]: Add .slnx to C#/F# LSP root detection #11929
Description
Feature hasn't been suggested before.
- I have verified this feature I'm about to request hasn't been suggested before.
Describe the enhancement you want to request
Modern .NET uses the ".slnx" file format for projects.
The current LSP NearestRoot implementation is only searching for the old ".sln" solution file format but nor for the modern ".slnx".
See Introducing support for SLNX, a new, simpler solution file format in the .NET CLI