* bump chia_rs to 0.31.0
* integrate new pos2 API from chia_rs into V2Prover
* fixup test_harvester_api mocking of Prover
* review-comments: rename get_quality() to get_string() on Quality protocol
* reivew comments
* fixup bump chia_rs
* restore quality string to bytes32
* stub chiapos2 API
* update block tools to support v2 plots when generating chains, as well as using the solve_proof() stub in the solver
* review comments