Apart from generator.php, the code in this folder comes from

https://wordpress.org/plugins/wicked-block-builder/

This code makes the blocks in the blocks folder work.

Generator.php is my file, which sets up the others, see below for how I think i did this.

The others are in (as at version 1.4.6)

wicked-block-builder/dist

generator.css
generator.js

wicked-block-builder/classes/rest-api/v1

class-generator-api.php
class-rest-api.php

generator.php is code that I think is created when you export a block to a plugin.  
So in the wicked-block-builder there is an option to export a block to a standalone plugin.  
This generates a plugin.zip file, and I think I took the code from that.