[Feature] Common JS to run once before test suite

[lukasradek]

Just like we have a JS setup to run before each test, it would be great to have a JS "pre-setup", that would run once per whole test. For example for generating random sequences for testing, which would then stay the same for all tests.

[m-paternostro]

This would be indeed a great feature. Besides the random sequences, it would also allow for defining constants for all tests. This is particular important when benchmarking code that use regex because we can precompile them as we would on a real application.