Implements the @llvm.aarch64.sve.dupq.lane intrinsic.
As specified in the ACLE, the behaviour of:
svdupq_lane_u64(data, index)
...is identical to:
svtbl(data, svadd_x(svptrue_b64(), svand_x(svptrue_b64(), svindex_u64(0, 1), 1), index * 2))
If the index is in the range [0,3], the operation is equivalent
to a single DUP (.q) instruction.
nit: auto *CIdx