Improve remote debugging tooling

Problem

Couldn't run remote debugging (aka, set breakpoints inside the running server code) with the instructions provided by the README.

Context

I followed the steps in the README for debuging functional tests but it didn't work.

After some research + trial-and-error, I was able to make it work with:

# Setting the breakpoint in the code
#   I've relied on the already exposed 12345, which I don't know if have another purpose
import epdb; epdb.serve(port=12345)

# Attaching pdb from another terminal
#   from here: https://github.com/ionelmc/python-remote-pdb#usage
sudo dnf install rlwrap socat
rlwrap socat - tcp:127.0.0.1:12345

But still, epdb doesn't have a very good documentation and is unmaintained in years.

Proposal

I'd like to have better builtin support for remote debugging out-of-the-box.

The idea I have for this is using remote-pdb, which has slighly better documentation and tooling. For example, it can be configured via envvars to integrate with regular breakpoints(). oci-env could set those envvars by default and we don't have to worry about porting and can use normal breakpoints() syntax.

Alternatives

1. Continue using epdb and update README instructions
2. Look another tool with convenient remote-debug capability and update README

Start with the README's “debugging functional tests” section and compare its epdb instructions with the issue's working remote-pdb example. Investigate how oci-env configures functional-test containers and how remote-pdb environment variables integrate with breakpoints(). Done means remote debugging works out of the box and the README documents the complete workflow.