Configure VS Code to auto-format code with YAPF (#707)

.style.yapf

@@ -0,0 +1,2 @@
+[style]
+based_on_style = google

.vscode/settings.json

@@ -5,8 +5,10 @@
     "editor.formatOnSave": false
   },
   "[python]": {
+    "editor.defaultFormatter": "ms-python.python",
     "editor.tabSize": 4
   },
+  "python.formatting.provider": "yapf",
   "python.linting.pylintEnabled": true,
   "python.linting.enabled": true,
   "python.linting.lintOnSave": true

.yapfignore

@@ -0,0 +1,2 @@
+third_party/*
+venv/*

dev-scripts/build-python

@@ -32,13 +32,7 @@ coverage run \
 coverage report
 
 # Check that source has correct formatting.
-yapf \
-  --diff \
-  --recursive \
-  --style google \
-  ./ \
-  --exclude=third_party/* \
-  --exclude=venv/*
+yapf --diff --recursive ./
 
 # Check correct sorting for imports.
 isort \