Add Optimas Ax generator tests

[shuds13]

Add tests for running Optimas Ax generators with libEnsemble.

This requires working with generators that produce _id. Also, deal with multi-task generator as required.

• Ax Generators (single/multi-fidelity / multitask). - Unexpected vars from suggest (not in H array).

Check

• Currently fixing nworkers to batch_size. Change to run using test harness command line settings.
• Re-enable running of full tests (REG_TEST_LIST = "test_*.py") - currently only runs new tests.
• Pydantic version range in pyproject - open upper bound again- currently pydantic = ">=2.11.7,<2.12"

[jlnav]

I'm seeing our dependencies being

dependencies = ["numpy", "psutil", "pyyaml", "tomli", "gest-api @ git+https://github.com/campa-consortium/gest-api@main", "pydantic"]

in our pyproject.toml.

Are you referring to optimas's version?