gatherBits

private fn

void gatherBits(ArrayData[]  chunks,  const  size_t[]  chunkStarts,
       const(size_t)[]  indices,  ref  BooleanBuilder b)

@safe

Gathers BOOLEAN value and validity bits at the given global indices, packing 64 output slots per builder word.

`chunks`	the source chunks
`chunkStarts`	the global start index of every chunk
`indices`	the global indices to gather, in order
`b`	the builder receiving the packed slots