convert : add compressed-tensors NVFP4 support (#21095)

* Refactored Compressed Tensors NVFP4 support for new base.py

* Support compressed-tensors NVFP4 conversion

* Moved Qwen MTP remap into filter_tensors

* simplify

* pathlib no longer used

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Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@scala.com>