isolate action code

Right now all action code that is run, has access to the host's node environment -- which is the developer's machine.
This includes the filesystem, running processes, etc. This will not be representative of a true serverless system which we are simulating.

Explore code isolation via the node `vm` module: https://nodejs.org/docs/latest-v18.x/api/vm.html
Take note that if the code to run uses `require` we will need to pass in the `require` loader, which may or may not be secure. In general this should not be a problem since we webpack the code.

Related:
1. https://github.com/node-inspector/node-inspector/issues/284
2. https://www.rocket.chat/blog/node-js-vm
3. https://github.com/laverdet/isolated-vm
4. https://github.com/Richienb/node-polyfill-webpack-plugin (note fs is not in there, since browsers do have this now, but we can easily add the fs fallback in)
5. https://blog.logrocket.com/how-to-protect-your-node-js-applications-from-malicious-dependencies-5f2e60ea08f9/
6. https://github.com/tschaub/mock-fs

Start by locating the action execution entry point in this repository; the issue does not name a file or test. Read Node's vm documentation and the linked isolation references, then define an isolation approach that accounts for require and filesystem access; the issue does not specify concrete completion criteria.

Written by the indexing model from the issue text.