Allow configuring the tokenizer in `Text2TextGenerationPipeline`

[tarekziade]

Feature request

The current behavior has hardcoded options for the tokenizer https://github.com/huggingface/transformers.js/blob/main/src/pipelines.js#L761-L775

Motivation

It would be nice to stick with the generic pipeline API and be able to pass through custom tokenizer options that are overwriting tokenizer.json

Your contribution

If the idea sounds good I can contribute the patch

[xenova]

Sure that's a good idea! We can move it up to the kwargs section 👍 (with defaults set accordingly).