Enable quantization of tied embeddings

[eldarkurtic]

Tied embeddings are usually implemented in a way that they subclass torch.nn.Embedding and then implement the custom parts to handle using of the same matrix for embeddings and for the LM head. This PR enables detecting these modules during quantization as their type is not Embedding, but rather something custom defined by the LLM implementation. However, they are all subclasses of torch.nn.Embedding which we can utilize to detect them.

Before this PR, quantization modifier couldn't find tied embeddings modules as their type is not torch.nn.Embedding.