SHM: segment detach

[yellowhatter]

Describe the feature

As part of #1697
Let's think about segment detach functionality. Currently, at SHM receiver side, attached segements are not detached and exist through all the process lifetime. We definitely need to develop some detach condition, otherwise that can cause unneeded segments to exist forever.

The problematic here is not in implementation, but rather in condition itself: when to detach the segment?

Too early detach will make us pay additional costs when we again receive an SHM buffer belonging to detached segment - we will attach this segment again.

I guess, to start with, we need just some timeout started from the last segment use....