model: add Ernie 4.5 MoE support (#14658)

model: add Ernie 4.5 MoE support (#14658)

* Add Ernie4.5 MoE

* Fix Flake errors.

* Properly encode/decode MoE layer step

* Correct tensor mappings (.weight)

* Pass and read n_ff_exp

* n_ff_shexp calculation and further minor changes

* Rope fixes.

* .gitignore fix

* Add unit32 cast for Linux builds

* Apply suggestions from code review

Co-authored-by: Sigbjørn Skjæret <redacted>
* Further fixes from code review

* Fix trailing whitespace

* Reenable missing experts error

* Code style from code review

Co-authored-by: Sigbjørn Skjæret <redacted>
* Fix non-MoE regression

Co-authored-by: Sigbjørn Skjæret <redacted>
---------

Co-authored-by: Sigbjørn Skjæret <redacted>