CoCa RoBERTa Attention Map Size Issue about open_clip

[rwightman]

@sandeepmukh
I think a few things wrong for this .... first, update to main branch.

Then, I think this is needed in CocaModel to replace current vocab_size logic btw text and multimodal text towers

        if getattr(text_cfg, "hf_model_name", None) is not None:
            vocab_size = getattr(self.text, "vocab_size", text_cfg.vocab_size)
        else:
            vocab_size = text_cfg.vocab_size

Also, the context_len used by tokenzier sources from text_cfg by default, so text_cfg and multimodal_cfg should have same context_len values in config (I think) to work best but I'm not 100% sure there.