feat: size script (#202)

## 📜 Description

Added `size.js` script which creates a package and prints zipped size.

## 💡 Motivation and Context

This is related to this
#201
PR. The reason why it handled in separate PR is because script in
#201
switches to target branch (`main`), but since the script is not
available in this branch - I can not verify that script works as
expected.

## 📢 Changelog

### CI
- added `scripts/size.js` file;

## 🤔 How Has This Been Tested?

Was tested in
#201

## 📝 Checklist

- [x] CI successfully passed

scripts/size.js

@@ -0,0 +1,5 @@
+const { exec } = require('child_process');
+
+exec('npm pack --json', function (error, stdout, stderr) {
+  console.log(JSON.parse(stdout)[0].size);
+});