MemorySegment based implementation of LongList

[artemananiev]

LongList interface in MerkleDb has several implementations, including Java heap and off-heap lists. Off-heap implementation relies on sun.misc.Unsafe to close its index chunks, which are Java direct byte buffers.

With JDK 25 support, a new implementation can be provided, based on MemorySegments. It would combine native buffer benefits (as off-heap) and well defined API to manage buffer lifecycle (as on-heap).