Added linaria in order to contribute to to-do's

[eirinikond]

Added linaria/mini-css-extract-plugin/file-loader and configuration for lianaria to webpack.commom.js

[anikethsaha]

Thanks a lot for the PR.
Actually you can notice that I have added the support for extensions or plugin kind of configuration using merg.config.js which is doing these optional features on top of the main basic boilerplate.
But now I am working on a whole new plugin architecture which includes a CLI and plugins support with deep integrations. I will try to roll out that one by the end of Feb. I hope to see this PR as a form of plugin after that like mern-plugin-linaria. If you want this thing to be supported soon, you need to make a template like these , and need to create a script for that to change the contents like these

I know these steps right now is pretty workaround thing, but It will be solid in next update.

Cheers 🎉