Foundry prbmath external test

[r0qs]

Fixes #13767.

This PR migrates the prb-math external tests script to python and add support to foundry.

The PR also adds an initial architecture to the python-based external tests. The idea was to allow us to easily migrate from different test frameworks as external projects change their dependencies.

I didn't migrate all the shellscripts yet, for instance, the store_benchmark_report still missing for the prb-math. But it would be nice to discuss some ideas around the current architecture.

Depends on: #13982, #14064 and #14140.

• The dependence on Cleanup base images and CI config #13982 is due to the change of the t_ems_ext, which was renamed to t_ext and now receives the image as parameter instead of only the nodejs version. This allows running some external tests on different base images, e.g. cimg/rust:1.66.1. The change was required since Foundry depends on rust and not nodejs. Actually, as we are now downloading the forge binary, rust is not needed.

• The dependence on External tests script refactor #14064 is based on the replacement of the old test/externalTests.sh by a python script that allows run one, multiple or all external tests.

• The dependence on Foundry ci setup #14140 is due to the new install_python3 and install_foundry CI commands.

TODO:

• Update external tests README (I think we can update the docs once we migrate the other tests to python as well. So we can have a PR that introduces the new way of setup a external test using the python-based suite)
• Add support to Foundry in parse_eth_gas_report.py (will be done in a future PR)
• Store Foundry benchmarks report (will be done in a future PR)

[cameel]

Here's more feedback.

I also pushed some new commits that address minor things that weren't worth starting a discussion.

[cameel]

I'm approving since this is already good enough.

There are still a few minor comments that I see you're in process of addressing and you need to squash, but I'm assuming all of that will be dealt with. Feel free to merge once you're done.