Split block bloom filter implementation.

Implementation of parquet bloom filter spec.

• Full runtime detection of cpu features, don't need to do target-cpu=native or manually turn on avx
• All stable rust
• Outputs same byte buffers on different systems. Completely cross-platform.
• no_std support
• relatively simple and low amount of code

• Only unsafe api. Safe API can be found at sbbf-rs-safe.
• Dynamic dispatch to methods. (Not sure if this will effect performance so much)
• On WASM, unlike other targets, need to do RUSTFLAGS="-C target-feature=+simd128" and use nightly if you want to enable SIMD accelerated version of filter. If user compiles without enabling simd128, they don't need to use nightly and the fallback implementation of a filter will be used.