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## Current Behavior
Plugin isolation communicates with workers via built-in node IPC with
forked processes. When doing this, the parent process will not exit
until the child process has exited, in case more messages would be sent.
This requires an explicit call to shut down the plugin workers.

We set this up as a `process.on('exit')` listener, to shutdown the
workers whenever the main Nx process dies. This is "fine", but requires
explicit calls to `process.exit` as node won't exit on its own
otherwise.

## Expected Behavior
To allow plugin workers to clean themselves up on exit, but not require
explicit `process.exit` calls, we need to detach them from the main
process and call `unref`. This only works when IPC is not being used. As
such, we need a different way to communicate with the worker.

This PR updates the communication method to mirror the daemon, and
communicate over a socket. Additionally, this PR enables isolation
during the Nx repo's E2E tests.

## Related Issue(s)
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merged. -->

Fixes #