Introduce DotNETUtil

* Apply in FSharpLanguageServer and CSharpLanguageServer
* CSharpLanguageServer: Disabled auto-install of .NET (does not work reliably)
  and remove corresponding test
* Remove TestFSharpLanguageServerSetup

test/solidlsp/fsharp/test_fsharp_basic.py

@@ -1,14 +1,10 @@
 import os
-import tempfile
 import threading
-from pathlib import Path
 from typing import Any
-from unittest.mock import Mock, patch
 
 import pytest
 
 from solidlsp import SolidLanguageServer
-from solidlsp.language_servers.fsharp_language_server import FSharpLanguageServer
 from solidlsp.ls_config import Language
 from solidlsp.ls_utils import SymbolUtils
 from test.conftest import is_ci
@@ -183,41 +179,3 @@ class TestFSharpLanguageServer:
 
         # This is a successful test - FsAutoComplete is working with F# files
         assert True, "F# language server can handle files successfully"
-
-
-@pytest.mark.fsharp
-class TestFSharpLanguageServerSetup:
-    """Test F# language server setup and configuration."""
-
-    def test_runtime_dependency_setup_without_dotnet(self) -> None:
-        """Test that setup fails gracefully when .NET is not installed."""
-        with patch("shutil.which", return_value=None):
-            with pytest.raises(RuntimeError, match=r"\.NET SDK is not installed"):
-                FSharpLanguageServer._setup_runtime_dependencies(Mock(), Mock())
-
-    def test_runtime_dependency_setup_with_dotnet(self) -> None:
-        """Test that setup works when .NET is available."""
-        mock_config = Mock()
-        mock_settings = Mock()
-
-        # Mock the ls_resources_dir to return a temp directory
-        with tempfile.TemporaryDirectory() as temp_dir:
-            with patch("shutil.which", return_value="/usr/bin/dotnet"):
-                with patch.object(FSharpLanguageServer, "ls_resources_dir", return_value=temp_dir):
-                    with patch("subprocess.run") as mock_run:
-                        # Mock successful dotnet version check
-                        mock_run.return_value.stdout = "8.0.100"
-                        mock_run.return_value.returncode = 0
-
-                        # Create a fake fsautocomplete executable
-                        fsharp_dir = os.path.join(temp_dir, "fsharp-lsp")
-                        os.makedirs(fsharp_dir, exist_ok=True)
-                        # Use .exe extension on Windows, matching production code
-                        exe_name = "fsautocomplete.exe" if os.name == "nt" else "fsautocomplete"
-                        fsautocomplete_path = os.path.join(fsharp_dir, exe_name)
-                        Path(fsautocomplete_path).touch()
-
-                        result = FSharpLanguageServer._setup_runtime_dependencies(mock_config, mock_settings)
-
-                        assert fsautocomplete_path in result
-                        assert "--adaptive-lsp-server-enabled --project-graph-enabled --use-fcs-transparent-compiler" in result