vertexfilter: Implement NEON versions for all filters
vertexfilter: Implement NEON versions for all filters

This is an initial implementation that converts Wasm SIMD implementation
to NEON. It was tested on Amazon A1 and results in substantial
performance improvements:

Scalar performance:
oct8 231.26 ms (0.13 GB/sec), oct12 231.22 ms (0.26 GB/sec), quat12 179.14 ms (0.33 GB/sec), exp 19.04 ms (3.13 GB/sec)

NEON performance:
oct8 62.71 ms (0.48 GB/sec), oct12 69.98 ms (0.85 GB/sec), quat12 73.33 ms (0.81 GB/sec), exp 19.06 ms (3.13 GB/sec)

zeux/meshoptimizer,zeux/meshoptimizer,zeux/meshoptimizer