Examine performance of individual data accessor methods of MemorySegmentIndexInput when IndexInputs are closed in other threads (deoptimizations,...)

Examine performance of individual data accessor methods of MemorySegmentIndexInput, as compared to the ByteBufferIndexInput. Specifically getByte, getShort, and getBytes.

This issue has been filed to raise awareness of a seemingly perf degradation of MemorySegmentIndexInput when used heavily in decompression, see https://github.com/dacapobench/dacapobench/issues/264. I've not yet investigated the low-level segment guards, but maybe there is something here (or in the VarHandles) that is not optimising?