[Task]: Rework the class loading system

### What needs to happen?

Hop uses a ton of class loaders, one for every plugin.
It's not clear how it's still needed. We can think of making a new plugin system that builds a single classpath with all the libraries of all the plugins in it.

### Issue Priority

Priority: 3

### Issue Component

Component: API

Start by mapping how Hop currently creates and uses one class loader per plugin, then review the API component's plugin-loading design. Define the intended single classpath approach and identify the compatibility and dependency questions that must be resolved before implementation.

Written by the indexing model from the issue text.