Allow spaces in outputpath

[MariovanZeist]

fixes: dotnet/aspnetcore#38702

Assume the following:

when using the following scripts in package.json

  "scripts": {
    "build": "npm run build:release",
    "build:Release": "webpack --mode production",
    "build:Debug": "webpack --mode development",
  }

When there are spaces in the output path,

The build output shows:
webpack --mode development "--output-path" "D:\My" "Projects\Redacted\src\MyLibrary.Components\obj\Debug\net6.0\clientassets/"

but should say:
webpack --mode development --output-path "D:\My Projects\Redacted\src\MyLibrary.Components\obj\Debug\net6.0\clientassets/"

(for readability I put the path part on the next line)

This PR fixes that.