WIP: wiring the vector manager up in synchronize

[friendlymatthew]

This is still a work in progress. This PR adds the wiring logic for FieldTypeVector.

What's been done

Base case:
The JSONLHandler will create a VectorPageManager upon first entry. Need to serialize the entry node.

Rest:
Given the correct BTree and BPTree pages, the VectorPageManager updates the hnsw, then writes information about the freshly inserted vector.

Todo

1. Currently a linked meta page is unique if it has a different FieldName and FieldType. However with a new storage data structure BTree, we also need to factor in TreeType as well.

2. FindOrCreateIndex() needs to return a list of unique pages. In the vector case, it should return two pages, the Id to Point mapping BTree and the Friends mapping BPTree.

hnsw.Hnsw will be stateful and it'll only be correct when handleJsonObject gets called last.

Additional thoughts:

• serialize the entry node case properly

[github-actions]

Benchmark results: https://github.com/kevmo314/appendable/actions/runs/10013366826/artifacts/1720414132