Run Prettier on all source files (#1648)

This commit updates `npm run format:all` to not only format .js files in
src/ and bin/, but also tests_config/ and scripts/, as well as all
jsfmt.spec.js files.

It also includes the result of running `npm run format:all`, except
changes to src/ and bin/.

scripts/sync-flow-tests.js

@@ -36,7 +36,7 @@ function syncTests(syncDir) {
         "Couldn't find any files to copy.",
         `Please make sure that \`${syncDir}\` exists and contains the flow tests.`
       ].join("\n")
-    )
+    );
   }
 
   const specContents = specFiles.reduce((obj, specFile) => {