message: Update debugger to 1.12.3
  This updates the debugger to the 1.12.3 version. At the same time this switches to the new VS CDN for the debugger. Lastly, this changes the package version to beta 3.
diff: {
  "name": "csharp",
  "publisher": "ms-vscode",
  - "version": "1.12.0-beta2",
  + "version": "1.12.0-beta3",
  "description": "C# for Visual Studio Code (powered by OmniSharp).",
  "displayName": "C#",
  "author": "Microsoft Corporation",
  },
  {
  "description": ".NET Core Debugger (Windows / x64)",
  - "url": "https://vsdebugger.azureedge.net/coreclr-debug-1-12-2/coreclr-debug-win7-x64.zip",
  - "fallbackUrl": "https://vsdebugger.blob.core.windows.net/coreclr-debug-1-12-2/coreclr-debug-win7-x64.zip",
  + "url": "https://download.visualstudio.microsoft.com/download/pr/10950340/4d5e39c15f4229a200bc1956621758fe/coreclr-debug-win7-x64.zip",
  + "fallbackUrl": "https://vsdebugger.blob.core.windows.net/coreclr-debug-1-12-3/coreclr-debug-win7-x64.zip",
  "installPath": ".debugger",
  "platforms": [
  "win32"
  },
  {
  "description": ".NET Core Debugger (macOS / x64)",
  - "url": "https://vsdebugger.azureedge.net/coreclr-debug-1-12-2/coreclr-debug-osx.10.11-x64.zip",
  - "fallbackUrl": "https://vsdebugger.blob.core.windows.net/coreclr-debug-1-12-2/coreclr-debug-osx.10.11-x64.zip",
  + "url": "https://download.visualstudio.microsoft.com/download/pr/10950340/4d5e39c15f4229a200bc1956621758fe/coreclr-debug-osx.10.11-x64.zip",
  + "fallbackUrl": "https://vsdebugger.blob.core.windows.net/coreclr-debug-1-12-3/coreclr-debug-osx.10.11-x64.zip",
  "installPath": ".debugger",
  "platforms": [
  "darwin"
  },
  {
  "description": ".NET Core Debugger (linux / x64)",
  - "url": "https://vsdebugger.azureedge.net/coreclr-debug-1-12-2/coreclr-debug-linux-x64.zip",
  - "fallbackUrl": "https://vsdebugger.blob.core.windows.net/coreclr-debug-1-12-2/coreclr-debug-linux-x64.zip",
  + "url": "https://download.visualstudio.microsoft.com/download/pr/10950340/4d5e39c15f4229a200bc1956621758fe/coreclr-debug-linux-x64.zip",
  + "fallbackUrl": "https://vsdebugger.blob.core.windows.net/coreclr-debug-1-12-3/coreclr-debug-linux-x64.zip",
  "installPath": ".debugger",
  "platforms": [
  "linux"
  