[Common] Move NVFP4 scale traits to a separate header

[kainzhong]

TODO: hum maybe should use NVIDIA#3392 instead

Description

Fix the CI compilation failure. The failure is because when we compile
transformer_engine/common/gemm/cublaslt_grouped_gemm.cu it includes
--> transformer_engine/common/cast/nvfp4/core_nvfp4.cuh which includes
--> transformer_engine/common/util/ptx.cuh
where ptx.cuh hits this assertion on CI

#35 50.63   /opt/transformerengine/transformer_engine/common/gemm/../cast/nvfp4/../../util/ptx.cuh(55): error: static assertion failed with "Compiled for the generic architecture, while utilizing family-specific features. Please compile for smXXXf architecture instead of smXXX architecture."
#35 50.63           static_assert(FamilySpecific == CurrentArch,
#35 50.63           ^
#35 50.63   /opt/transformerengine/transformer_engine/common/gemm/../cast/nvfp4/../../util/ptx.cuh(55): note #3453-D: the final comparison was 0 == 1000
#35 50.63           static_assert(FamilySpecific == CurrentArch,
#35 50.63                                        ^
#35 50.63             detected during:

because gemm/cublaslt_grouped_gemm.cu is listed under transformer_engine_cuda_sources so it's not compiled by "f" suffix (those should be listed under transformer_engine_cuda_arch_specific_sources)

This PR moves the newly added chage to a separate file which doesn't include ptx.cuh to avoid this compile time assertion.

TODO: or I should split ptx.cuh to ptx.cuh and ptx_arch_spec.cuh instead

Fixes # (issue)

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

• Moved NVFP4 scale trait to a separate file

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