Perf: Split query distance argument conversion and the further distance computation in heuristic_prune_neighbors

[Vika-F]

svs::distance::Convert class that performs ISA-specific the argument conversion was added.

The Convert::apply function assumes that the destination pointer is 64-byte aligned. This was done intentionally in order to use aligned loads in the distance computations further.

svs::distance::PreconvertedArgument class was added. It allows to allocate the storage for the pre-converted query argument once during the call to heuristic_prune_neighbors.