Find out the optimal frequency of structural uniqueness verification

It is important to filtrate individuals frequently since now the same structurally identical individuals are rapidly accumulating. However, too frequent filtering can significantly slow down the evolution process.

The task it to measure how much time it takes for one check of structural uniqueness in relation to the evaluation of the generation metric and, if a little, implement a more frequent check. Not the structural uniqness check is implemented [here](https://github.com/aimclub/GOLEM/blob/main/golem/core/optimisers/populational_optimizer.py#L99).

Also, there is a [subtask](https://github.com/aimclub/GOLEM/issues/134) that must be done to speed up verification.