Dflash support for nemotron-3.5 (#26905)

Dflash support for nemotron-3.5 (#26905)

* conversion: skip untrained DFlash embeddings

* Add Nemotron DFlash support

* Add DFlash NVFP4 support

* Address review comments

* add missing output_s for nvfp4

* Include change for keeping residual for last layer also if requested in future dflash models

* Update conversion/qwen.py

Defensive check, not needed

Co-authored-by: Sigbjørn Skjæret <redacted>
* Fixing bug introduced by merge conflict

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Co-authored-by: Sigbjørn Skjæret <redacted>