Add sort keys and sort imports lint rules, and enable fix+format on save (#1209)

* Add sort keys rule and update configs so it works

Bump version of flowtype eslint plugin to fix bugs with autofixing

* Add sort imports fixable lint rule

* Run lint fix and prettier on whole repo 

* Fix unit tests broken by key sorting

scripts/error-codes/transform-error-messages.js

@@ -42,7 +42,7 @@ module.exports = function (babel) {
           const errorMsgExpressions = Array.from(node.arguments.slice(2));
           const errorMsgQuasis = errorMsgLiteral
             .split('%s')
-            .map((raw) => t.templateElement({raw, cooked: String.raw({raw})}));
+            .map((raw) => t.templateElement({cooked: String.raw({raw}), raw}));
 
           // Outputs:
           //   `A ${adj} message that contains ${noun}`;