Bug fixes & minor changes

• Introduce better support of using external abseil and protobuf https://github.com/google/sentencepiece/issues/869
• Build universal binary in OSX release package https://github.com/google/sentencepiece/issues/892
• Add the set_min_log_level function to python to change the loglevel from the python wrapper. https://github.com/google/sentencepiece/issues/893
• Uses the logsumexp techniques in marginal probabilities of n-best tokenization to avoid underflow.
• Support Python 3.12 https://github.com/google/sentencepiece/issues/932
• Improves the thread utilization in batch encoding/decoding.
• Fix nasty bug in BPE position encoding.
• Fix bugs in the handling of duplicated bigrams