Far better VSCode intellisense support using clangd. (#20382)

.vscode/settings.json

@@ -26,6 +26,9 @@
     },
     "python.formatting.provider": "yapf",
     "[json]": {
-	    "editor.formatOnSave": false
-    }
+        "editor.formatOnSave": false
+    },
+    "clangd.arguments": [
+        "--header-insertion=never"
+    ]
 }