Replace workspaceRoot with workspaceFolder. (#20306)

workspaceRoot has been deprecated as per https://code.visualstudio.com/docs/editor/variables-reference#_why-isnt-workspaceroot-documented

docs/tutorial/debugging-main-process-vscode.md

@@ -17,10 +17,10 @@ $ code electron-quick-start
       "name": "Debug Main Process",
       "type": "node",
       "request": "launch",
-      "cwd": "${workspaceRoot}",
-      "runtimeExecutable": "${workspaceRoot}/node_modules/.bin/electron",
+      "cwd": "${workspaceFolder}",
+      "runtimeExecutable": "${workspaceFolder}/node_modules/.bin/electron",
       "windows": {
-        "runtimeExecutable": "${workspaceRoot}/node_modules/.bin/electron.cmd"
+        "runtimeExecutable": "${workspaceFolder}/node_modules/.bin/electron.cmd"
       },
       "args" : ["."],
       "outputCapture": "std"