[coverage] Fix non source-mapped coverage issue

[Desplandis]

Description

The coverage was not correct since there was no source-map between the babel-compiled output and the original source code. This led to incorrect coverage reports (issue first found by @ftoromanoff) since those were based on the babel-compiled output.

This PR fixes on our unit tests:

• the aforementioned source-map issue by using our own node module hook instead of the babel-register-esm one.
• experimental warnings when using --experimental-loader options, we now use node:module.register() (not supported by babel-register-esm).
• [BABEL] Note: The code generator has deoptimised the styling of [...]/node_modules/[...] as it exceeds the max of 500KB. warnings, since we now ignore compilation of modules in node_modules (not done by babel-register-ems but previously done by @babel/register).

Further info:

• Node module API