[JAX] Update helper tests

[jberchtold-nvidia]

Description

Updates tests/jax/test_helper.py to include tests for fp8_autocast and QuantizeConfig for the new scaling modes, MXFP8 block scaling and Current scaling.

Type of change

• Documentation change (change only to the documentation, either a fix or a new content)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Infra/Build change
• Code refactoring

Changes

• Updates test_helper.py to include tests for the new scaling modes, MXFP8 block scaling and Current scaling
• Adds a new QuantizeConfig CurrentScalingQuantizeConfig for using fp8_autocast with current scaling

Checklist:

• I have read and followed the contributing guidelines
• The functionality is complete
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[jberchtold-nvidia]

/te-ci L0