Add inputs_embeds param to ModernBertModel (#35373)
* update modular_modernbert -- add inputs_embeds param to ModernBertModel
* Fix implementation issues; extend to other classes; docstring
First of all, the inputs_embeds shouldn't fully replace `self.embeddings(input_ids)`, because this call also does layer normalization and dropout. So, now both input_ids and inputs_embeds is passed to the ModernBertEmbeddings, much like how BertEmbeddings is implemented.
I also added `inputs_embeds` to the docstring, and propagated the changes to the other model classes.
I also introduced an error if input_ids and input_embeds are both or neither provided.
Lastly, I fixed an issue with device being based solely on input_ids with attention_mask.
* Propagate inputs_embeds to ModernBertForMaskedLM correctly
Also reintroduce inputs_embeds test
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Co-authored-by: Tom Aarsen <Cubiegamedev@gmail.com>
