Added token selector

[menamerai]

Adds the function to make token selector from tokenizer's vocab. Basically, the input should be a dict[str, int] that you can get from calling tokenizer.get_vocab(). We could also change the input to the tokenizer instead, but it's like that for now.

The function returns two thing, the first thing is the actual widget itself. If you want the string tokens from the widget, you can call widget.value. The second thing is a list of tokens ids that correspond to the selected tokens that are continually updated.