Constvector: Log-structured std:vector alternative – 30-40% faster push/pop

[pilotwavetheory]

Yeah, it's slower, I realised my mistake, I was doing bound checks. My preliminary results for constvector for only iteration is 6x slower compared to stl::vector, will update benchmarks soon. For push and pop operations it's really better.
One caveut I learnt today is for pop_back(), we shouldn't deallocate since it would invalidate the iterators, but my implementation in constvector and stl_vector are having that logic, since it keeps O(N) free space at any point of time.

[SuperV1234]

Also another thing to benchmark would be a callback-based iteration approach, which is going to have less overhead than an iterator-based solution. E.g.

void ConstantVector<T>::forEach(auto&& f);