Summary:
This diff adds logic to create Vector LSM for vector indices.
And forward read/write queries to it.

The diff contains following restrictions, that should be fixed in followup diffs.
1) Auxiliary data is stored into memory, so restart is not supported.
2) Vector LSM is not created after restart.
3) Colocation not supported.
4) Read and write logic contains temporary code to handle requests in the current format. While in final design we should receive requests that takes into account that index is located on the same tablet as the main table.
5) Only data received via applied transaction is taken into account. Need to add intents DB scan and non transactional writes.
Jira: DB-14014

Test Plan: PgVectorIndexTest.Simple

Reviewers: arybochkin, tnayak

Reviewed By: arybochkin

Subscribers: ybase, yql

Tags: #jenkins-ready

Differential Revision: https://phorge.dev.yugabyte.com/D39849