add .vscode folder so we can share settings with everyone that is contributing (firefox-devtools#4987)

Author: joshunger

.gitignore

@@ -5,7 +5,6 @@ configs/local.json
 npm-debug.log
 assets-error.log
 .idea/
-.vscode/
 /firefox
 lerna-debug.log
 assets-error.log

.vscode/extensions.json

@@ -0,0 +1,7 @@
+{
+  "recommendations": [
+    "dbaeumer.vscode-eslint",
+    "esbenp.prettier-vscode",
+    "flowtype.flow-for-vscode"
+  ]
+} 

.vscode/settings.json

@@ -0,0 +1,6 @@
+{
+  "flow.pathToFlow": "${workspaceRoot}/node_modules/.bin/flow",
+  "eslint.autoFixOnSave": true,
+  "prettier.eslintIntegration": true,
+  "javascript.validate.enable": false
+}