[O# Parity] Support dotnet script (.csx) files

Type: Bug

## Issue Description ##

## Steps to Reproduce ##
1. Create folder `md scripting`
1. Navigate to the folder `cd scripting`
1. Create a scripting project `dotnet script init`
1. Add a file `bye.csx`
1. Add some code into this file, e.g. `Console.WriteLine("test");`

## Expected Behavior ##

The syntax highlighting works for file `bye.csv`

## Actual Behavior ##

- There is no syntax highlighting.
- The error `Request textDocument/signatureHelp failed` appears
- The output log shows another error:

```
Using dotnet configured on PATH
Dotnet path: C:\Program Files\dotnet\dotnet.exe
Activating C# + C# Dev Kit + C# IntelliCode...
[Info - 4:07:33 PM] [Program]Language server initialized
[Error - 4:07:50 PM] [LanguageServerHost]System.InvalidOperationException: Unexpected false - line 68
at Roslyn.Utilities.Contract.Fail(String message, Int32 lineNumber) in /_/src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Core/Utilities/Contract.cs:line 154
at Microsoft.CodeAnalysis.CSharp.SignatureHelp.InvocationExpressionSignatureHelpProviderBase.GetAccessibleMethods(InvocationExpressionSyntax invocationExpression, SemanticModel semanticModel, ISymbol within, IEnumerable`1 methodGroup, CancellationToken cancellationToken) in /_/src/Features/CSharp/Portable/SignatureHelp/InvocationExpressionSignatureHelpProviderBase_MethodGroup.cs:line 68
at Microsoft.CodeAnalysis.CSharp.SignatureHelp.InvocationExpressionSignatureHelpProviderBase.GetItemsWorkerAsync(Document document, Int32 position, SignatureHelpTriggerInfo triggerInfo, SignatureHelpOptions options, CancellationToken cancellationToken) in /_/src/Features/CSharp/Portable/SignatureHelp/InvocationExpressionSignatureHelpProvider.cs:line 98
at Microsoft.CodeAnalysis.SignatureHelp.AbstractSignatureHelpProvider.GetItemsAsync(Document document, Int32 position, SignatureHelpTriggerInfo triggerInfo, SignatureHelpOptions options, CancellationToken cancellationToken) in /_/src/Features/Core/Portable/SignatureHelp/AbstractSignatureHelpProvider.cs:line 245
at Microsoft.CodeAnalysis.LanguageServer.Handler.SignatureHelpHandler.HandleRequestAsync(TextDocumentPositionParams request, RequestContext context, CancellationToken cancellationToken) in /_/src/Features/LanguageServer/Protocol/Handler/SignatureHelp/SignatureHelpHandler.cs:line 58
at Microsoft.CommonLanguageServerProtocol.Framework.QueueItem`3.StartRequestAsync(TRequestContext context, CancellationToken cancellationToken)
[Error - 4:07:50 PM] Request textDocument/signatureHelp failed.
Message: Unexpected false - line 68
Code: -32000
[object Object]
Using dotnet configured on PATH
```

## Logs ##

### C# log ###
Post the output from Output-->C# here

### C# LSP Trace Logs ###
Post the output from Output-->C# LSP Trace Logs here. Requires `dotnet.server.trace` to be set to `Trace`

## Environment information ##

**VSCode version**: 1.82.2
**C# Extension**: 2.1.2
**Using OmniSharp**: false

Dotnet Information
Error running dotnet --info: Error: Command failed: C:\Program Files\dotnet\dotnet.exe --info
'C:\Program' is not recognized as an internal or external command,
operable program or batch file.

'C:\Program' is not recognized as an internal or external command,
operable program or batch file.

Visual Studio Code Extensions

|Extension|Author|Version|Folder Name|
|---|---|---|---|
|csdevkit|ms-dotnettools|0.4.10|ms-dotnettools.csdevkit-0.4.10-win32-x64|
|csharp|ms-dotnettools|2.1.2|ms-dotnettools.csharp-2.1.2-win32-x64|
|dotnet-interactive-vscode|ms-dotnettools|1.0.4461040|ms-dotnettools.dotnet-interactive-vscode-1.0.4461040|
|jupyter|ms-toolsai|2023.8.1002501831|ms-toolsai.jupyter-2023.8.1002501831-win32-x64|
|jupyter-keymap|ms-toolsai|1.1.2|ms-toolsai.jupyter-keymap-1.1.2|
|jupyter-renderers|ms-toolsai|1.0.17|ms-toolsai.jupyter-renderers-1.0.17|
|LiveServer|ritwickdey|5.7.9|ritwickdey.liveserver-5.7.9|
|msbuild-project-tools|tintoy|0.4.9|tintoy.msbuild-project-tools-0.4.9|
|pdf|tomoki1207|1.2.2|tomoki1207.pdf-1.2.2|
|powershell|ms-vscode|2023.6.0|ms-vscode.powershell-2023.6.0|
|python|ms-python|2023.16.0|ms-python.python-2023.16.0|
|run-on-save|pucelle|1.6.0|pucelle.run-on-save-1.6.0|
|vscode-dotnet-pack|ms-dotnettools|1.0.12|ms-dotnettools.vscode-dotnet-pack-1.0.12|
|vscode-dotnet-runtime|ms-dotnettools|1.7.3|ms-dotnettools.vscode-dotnet-runtime-1.7.3|
|vscode-jupyter-cell-tags|ms-toolsai|0.1.8|ms-toolsai.vscode-jupyter-cell-tags-0.1.8|
|vscode-jupyter-slideshow|ms-toolsai|0.1.5|ms-toolsai.vscode-jupyter-slideshow-0.1.5|
|vscode-pylance|ms-python|2023.9.20|ms-python.vscode-pylance-2023.9.20|
|vscodeintellicode-csharp|ms-dotnettools|0.1.26|ms-dotnettools.vscodeintellicode-csharp-0.1.26-win32-x64|;

Extension version: 2.1.2
VS Code version: Code 1.82.2 (abd2f3db4bdb28f9e95536dfa84d8479f1eb312d, 2023-09-14T05:55:25.390Z)
OS version: Windows_NT x64 10.0.19044
Modes:

System Info

|Item|Value|
|---|---|
|CPUs|11th Gen Intel(R) Core(TM) i9-11950H @ 2.60GHz (16 x 2611)|
|GPU Status|2d_canvas: enabled
canvas_oop_rasterization: enabled_on
direct_rendering_display_compositor: disabled_off_ok
gpu_compositing: enabled
multiple_raster_threads: enabled_on
opengl: enabled_on
rasterization: enabled
raw_draw: disabled_off_ok
video_decode: enabled
video_encode: enabled
vulkan: disabled_off
webgl: enabled
webgl2: enabled
webgpu: enabled|
|Load (avg)|undefined|
|Memory (System)|63.67GB (48.67GB free)|
|Process Argv|. --crash-reporter-id 9b73ea97-bda1-4db3-9fce-24ce43b1d8af|
|Screen Reader|no|
|VM|0%|

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dsvsc013:30795093
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```