Off-heap storage for RAFT log

In IGNITE-17334, we'll build a volatile log storage using a simple on-heap data structure. We need to replace it with an off-heap structure (probably, using page memory) to avoid GC pressure.

When using page memory, we could allocate a single region for all RAFT groups' log storages and allocate some memory budget to each RAFT group.

The description is not too precise, some research is needed.