Add onheap caches to benchmarks

[maypok86]

Clarification and motivation

1. Now offheap caches are included in the benchmarks: bigcache and fastcache. Comparison with which does not look fair.
2. I would like to add more different implementations to the comparisons in the throughput benchmarks, because very few implementations are used now.

Now we need to select those implementations.

Acceptance criteria

1. Added new implementations to comparisons and removed offheap caches.
2. Updated README.