convert: add MiMo-V2.6 support (#29257)
* convert: add MiMo-V2.6 support
Hoist the K3 mxfp4 conversion repack into base.py so it can be reused
Remove decoder from mmproj convert
* Update conversion/mimo.py
* fix: use autoparser
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Co-authored-by: Sigbjørn Skjæret <sigbjorn.skjaeret@huggingface.co>
Co-authored-by: Piotr Wilkin <piotr.wilkin@syndatis.com>
