[Model] Add support for GraniteMoeShared models

[tjohnson31415]

Adds support for the granitemoeshared model type which is based on granitemoe but with the addition of a shared experts layer. A preview model with this architecture can be found at ibm-research/moe-7b-1b-active-shared-experts.

transformers support for this GraniteMoeShared model was recently merged and requires transformers >= v4.49.0