Worker example

This plugin demonstrates how to create a Worker and, within it, use transformers.js for text classification.

At present, this plugin only works on desktop. However, it should also be possible to load the Worker from a plugin panel or dialog on mobile (but not web).

Notes:

plugin.config.json was updated to target web. This allows the plugin to load transformers.js from the worker without depending on node-loader.
- This simplifies the build process and should make it easier to add mobile and web support to this plugin.
WASM files and other assets are copied by tools/copyAssets.js.