workerize-loader and webpack 5

[3xtr4t3rr3str14l]

The workerize-loader plugin that we are using does not support webpack 5 (pkg issue tracked here: developit/workerize-loader#77). So we have to use webpack 4 for now. It also doesn't look like the package is being maintained much as this issue has been outstanding for a while despite there being 2 PRs in the package repo to solve the issue.

We could:

1. wait for the workerize-loader issue to be resolved
2. find a fork of workerize-loader that supports webpack 5
3. replace workerize-loader with something else that does the same thing
4. ???

[dapplion]

I would try

replace workerize-loader with something else that does the same thing