A bunch of constraints to AnyVectorArrayBuffer are too strict

There are constraints on many `AnyArrayBuffer where Dispatch == VectorArrayDispatch` that really should be `AnyArrayBuffer where Dispatch: VectorArrayDispatch`. I couldn't get it to compile at the time but now that we have more parts working maybe we can figure out how to change these. Many are interrelated so one might need to change them all at once.

Search the repository for `AnyArrayBuffer where Dispatch == VectorArrayDispatch` and inspect the related `AnyVectorArrayBuffer` constraints. Start by compiling the affected Swift code to identify which declarations are interdependent. Done means the relevant constraints use the intended protocol form and the project compiles successfully.

Written by the indexing model from the issue text.