Add .npmignore file to slim up npm package

### Instructions

To reduce disk size of the npm package we need to create a .npmignore.

<img width="264" alt="image" src="https://user-images.githubusercontent.com/328965/191116395-61984962-17c1-4fd9-9a6a-d2b6bfc95792.png">


### Problem

Right now we are including all the things in the npm package like .changesets file.
