Improve sorting logic in NeighborArray

### Description

The legacy sorting logic in NeighborArray below takes long N^2 in worst case, as it is a simple insertion sort and pushes/copies the rest of the array towards the end for each `uncheckedIndex`.

https://github.com/apache/lucene/blob/d87b4f3881511092bb2a5ec7530e7418157c16fc/lucene/core/src/java/org/apache/lucene/util/hnsw/NeighborArray.java#L152

I think it has a lot of scope for improvement and I'm attaching a PR below and opening a discussion for same.

Start by reading the sorting logic in lucene/core/src/java/org/apache/lucene/util/hnsw/NeighborArray.java around line 152. Understand how uncheckedIndex ordering and array contents are preserved, then inspect the relevant Lucene tests or benchmarks before changing the algorithm. Done means sorting is measurably improved without changing the expected neighbor ordering.

Written by the indexing model from the issue text.