Extension recommendations are out of date.

[cgranade]

As reported by @devlead (#34):

…the C# extension has changed its name from "ms-vscode.csharp" to "ms-dotnettools.csharp", this means all extensions depending on it needs to be updated and all repositories with extension.json containing

"recommendations": [
    "ms-vscode.csharp"
 ]

or you get errors like