[V1][Draft] Jump-forward decoding

[aarnphm]

This PR aims to add support for jump-forward decoding by introducing the following API:

• For Grammar class:
  • jump_forward_string: returns the longest jf-able string from the FSM
  • find_token_divergence: returns the index of shared outputs ids between (prev_output) and (prev_output+jf_string) and handle FSM accordingly

--wip--

Signed-off-by: Aaron Pham [email protected]

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[aarnphm]

Will ping once it is ready, discussing with Yixin atm to clear up some confusion