Support batch Encoding in tsfile cpp.

During the TsFile write process, encoding is one of the most time-consuming operations. In a complete write pipeline, encoding typically accounts for around 50% of the total execution time. Vectorizing the encoding and decoding processes can significantly improve write performance.

The issue names no files, tests, or entry points. Start by locating the C++ TsFile write pipeline and its encoding path, then define the batch-encoding scope and a performance comparison; done should include vectorized batch encoding and evidence of improved write performance.

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