Add and configure ESLint and update configuration for Prettier (#617)

* Add ESLint, update Prettier

* Update docs

* Update tests

* Update licenses

* Fix review points

docs/contributors.md

@@ -60,6 +60,7 @@ Pull requests are the easiest way to contribute changes to git repos at GitHub.
 
 - To implement new features or fix bugs, you need to make changes to the `.ts` files, which are located in the `src` folder
 - To comply with the code style, **you need to run the `format` script**
+- To lint the code, **you need to run the `lint:fix` script**
 - To transpile source code to `javascript` we use [NCC](https://github.com/vercel/ncc). **It is very important to run the `build` script after making changes**, otherwise your changes will not get into the final `javascript` build
 
 **Learn more about how to implement tests:**