enable google Javascript formatter

Add eslint bazel rule support so that javascript files can be linted
using google javascript formatting guidelines.

eslint can be ran with following command :
    bazel test lint_test

if javascript files are formatted correctly according to google
javascript formatting guidelines then above command passes successfully
otherwise above command fails with path to "test.log" file which
contains information about the rule that is violated.

following command can be used for formatting javascript files :
    bazel run lint_test -- --fix /path/to/file.js

also update zuul configuration to run eslint rule in zuul CI

also fix following lint error reported by eslint :
 error  Missing @license  jsdoc/require-file-overview

References :
https://gerrit.googlesource.com/gerrit/
    +/refs/heads/stable-3.2/tools/js

https://gerrit.googlesource.com/gerrit/
    +/refs/heads/stable-3.2/package.json

https://gerrit.googlesource.com/plugins
    /codemirror-editor/+/refs/heads/master/.eslintrc.json

".eslintrc" is referenced from above location since its formatted
there.

Change-Id: I65356de70c4eeb4cbce1dbc001cbf214a3477fa5
11 files changed