Tools: add a tool to check that no translations are missing

[warpdesign]

With already 3 translations, it will be easy to miss/forget to translate a string. There should be a tool that's run on precommit/prepush that checks that all strings from en.js are translated.

There could be something useful here: https://www.i18next.com/overview/plugins-and-utils

[prajwalhaniya]

I tried implementing this in my local development, I am able to parse the JSON files through i18next-parser. But, I am not able to generate the output to a specific folder, so that I can compare them and give an output of missing strings. Am I doing it right? I am stuck a little at this point.
I have created a folder called public and locales for test purposes.