Update Roslyn to .NET 9 (#7946)

Author: dibarbet

CONTRIBUTING.md

@@ -73,7 +73,7 @@ This section shows how to set up local Razor or Roslyn language servers for debu
 1. Clone the [Roslyn repository](https://github.com/dotnet/roslyn). This repository contains the Roslyn server implementation.
 2. Follow the build instructions provided in the repository.
 
-The server DLL is typically at `$roslynRepoRoot/artifacts/bin/Microsoft.CodeAnalysis.LanguageServer/Debug/net8.0/Microsoft.CodeAnalysis.LanguageServer.dll`, but this may vary based on the built configuration.
+The server DLL is typically at `$roslynRepoRoot/artifacts/bin/Microsoft.CodeAnalysis.LanguageServer/Debug/net9.0/Microsoft.CodeAnalysis.LanguageServer.dll`, but this may vary based on the built configuration.
 
 #### Razor
 
@@ -116,7 +116,7 @@ In your workspace `settings.json` file, add the following lines:
 
 ```json
 "dotnet.server.waitForDebugger": true,
-"dotnet.server.path": "<roslynRepoRoot>/artifacts/bin/Microsoft.CodeAnalysis.LanguageServer/Debug/net8.0/Microsoft.CodeAnalysis.LanguageServer.dll"
+"dotnet.server.path": "<roslynRepoRoot>/artifacts/bin/Microsoft.CodeAnalysis.LanguageServer/Debug/net9.0/Microsoft.CodeAnalysis.LanguageServer.dll"
 ```
 
 Replace <roslynRepoRoot> with the actual path to your Roslyn repository.

package.json

@@ -37,7 +37,7 @@
     }
   },
   "defaults": {
-    "roslyn": "4.14.0-1.25074.7",
+    "roslyn": "4.14.0-1.25078.4",
     "omniSharp": "1.39.12",
     "razor": "9.0.0-preview.25064.4",
     "razorOmnisharp": "7.0.0-preview.23363.1",

src/lsptoolshost/dotnetRuntimeExtensionResolver.ts

@@ -14,9 +14,9 @@ import { CSharpExtensionId } from '../constants/csharpExtensionId';
 import { readFile } from 'fs/promises';
 import { IDotnetAcquireResult, IDotnetFindPathContext } from './dotnetRuntimeExtensionApi';
 
-const DotNetMajorVersion = '8';
+const DotNetMajorVersion = '9';
 const DotNetMinorVersion = '0';
-const DotNetPatchVersion = '10';
+const DotNetPatchVersion = '1';
 export const DotNetRuntimeVersion = `${DotNetMajorVersion}.${DotNetMinorVersion}.${DotNetPatchVersion}`;
 
 /**