Improve vset pvector using SIMD instructions

[ranshid]

vset is a new DS used in order to track expired fields in hash objects. The vset is making use of different bucket encodings, one of them is a pointer vector which is maintained both sorted and unsorted. Operations like find, swap and sort can potentially be optimized using SIMD instructions.

[ranshid]

note that this will be handled by @ahmadbelb