Nothing should ever query re_data_store directly

[teh-cmc]

These low-level APIs are only meant to be used as building blocks for the higher-level query APIs.

Everything else should go through the query crates, in order to try and centralize/share as much as possible of all the logic that goes on top of fetching cells (resolving promises, handling errors, handling nullability, etc).

[teh-cmc]

I made some progress on this but quickly realized there was much more tech debt than I anticipated on this front.

I don't want to dive into yet another big refactoring right now, so postponing.