[META] Use Prefetch api of IndexInput for Vectors

[navneet1v]

Description

Creating this Meta issue to track all the ideas and places where we can use prefetch functionality of Lucene for Vectors.

Lucene Issue on Prefetch: apache/lucene#13179

Based on the deep-dive what I can see is currently the prefetch is not added for KNNVectorValues interface, but the IndexInput has the prefetch. We might need to make some changes in the KNNVectorValues so that we can expose the prefetch logic on a docId(like this: https://github.com/apache/lucene/blob/e8e179cd4553b503dc529179beb7c6290202acf0/lucene/core/src/java/org/apache/lucene/index/TermVectors.java#L44) rather than use the low level apis of IndexInput.

Tasks

• implement docId based prefetch in Lucene for KNNVectorValues
• Use IndexInput#prefetch in Exact search #2423
• Use prefetch to reduce the merge time for vector segments
• Use prefetch to do warmup for Lucene Index.