feat: [support logit_bias for OpenAI API compatible]

[nguyenhoangthuan99]

Problem
logit_bias map Optional Defaults to null.

Modify the likelihood of specified tokens appearing in the completion. Accepts a JSON object that maps tokens (specified by their token ID in the tokenizer) to an associated bias value from -100 to 100. Mathematically, the bias is added to the logits generated by the model prior to sampling. The exact effect will vary per model, but values between -1 and 1 should decrease or increase likelihood of selection; values like -100 or 100 should result in a ban or exclusive selection of the relevant token.

-> need to confirm llamacpp support this or not, but this might be nice to have feature.

reference: https://platform.openai.com/docs/api-reference/chat/create#chat-create-logit_bias

related issue: https://github.com/janhq/internal/issues/160

[gabrielle-ong]

✅ QA: Logit_bias 100 vs -100:
logit_bias = 100 => exclusive selection of the word "under"
logit_bias = 10 => increased selection of the word "under"
logit_bias = 0 => normal response