Replace the zlib library with zstd or lz4

[bqminh]

Currently IQ-TREE uses zlib to compress files such as the checkpoint files. However, zlib is getting (quite) slow for large datasets, which can become a bottleneck for very large alignment with lots of partitions. Better to use much modern and high performance libraries such as zstd (https://github.com/facebook/zstd) or lz4 (https://github.com/lz4/lz4).